Help needed to work out what has just happened!!

Hi, I new to this forum and really need some help with what has just happened to me!
I met my partner two years ago on an internet site, we eventually met up and got on really well. It was not long before we was pretty much seeing each other every night. She did seem to have low self-esteem, insecure, suspicious and a bit clingy but I did not mind as I really liked her even though she would come out with some rather bizarre of the wall remarks. She also seemed to have periods where she was struggling with depression and I tried to encourage her to exercise and to eat healthy as I have had issues when I was younger and found that it helped greatly
She then began to tell me about her life, how she was sexually abused by her farther but had no memory of this and was told by her sisters (who also was abused) and mother. Her mom herself back then was an alcoholic and even broke my girlfriend’s nose! She was also raped when she was 14 which sent her into some sort of turmoil where she had an eating disorder which the doctors could not understand as she would eat but pretty much be sick straight after! She was also expelled from school due to bad behaviour at this time! She had also moved house ten times in ten years which I found bizarre, I even said to her that it like your running away from something
She had a numerous of other incidents happen to her over the years including a period of taking heroin! She also has a history of extreme drug, alcohol abuse, gambling and self harm, I myself had a history of drug, alcohol abuse, self-harming and had depression myself, so understood her pain. She also has a history of violence including with every partner has been with and in getting into fights when she was out, some of family said you want to watch her as she is a bit wild, but she seemed fine to me so I just ignored the remarks! She had been diagnosed for having depression and had been on anti-depressant and been to counselling but she said the anti-depressants made her worse.
She has three girls,( I also have three girls) which I grew very close to and adored me back, her oldest even seen me as her farther due to have no contact with her real dad. Her family where over the moon when she met me and they was surprised at how much she seemed to adore me. She even said that I was the first person that she loved and trusted me with her life. She also use to say how lucky she was to of met me and could not imagine life without me! Even her friends where amazed at how much she seemed to love me, everyone said how perfect we was for one another. She gave me control over her money as she was no good with it and even managed to clear the debt that she had
Overall the relationship was a good one, we never really argued and always managed to talk things through, yes we did have our moments but overall it was a good relationship and we were both very close. We got engaged and was planning on getting married this year, we even had brought the wedding dress and nine bridesmaid dresses, three for her sisters, three for her girls and three for my girls. She took pictures with them all in them and sent them out to all her family and mine. She even did not care about a big wedding, she said that she would just marry me in register office as all she wanted was to be my wife and spend the rest of her life with me. I sold my house earlier this year and moved in with her, all of this was her idea and was what she wanted
She one sister started to become jealous of us and she was the closest sister to my girlfriend and she did not like that her sister was doing well and had found someone who she was happy with. She started to try and make life as difficult as possible for us and caused us a lot of stress! She started saying things behind our backs that got back to us including that I was controlling her! Her family said that she was just jealous and to ignore her, my girlfriend even started to realise other things that her sister had done before to try and ruin things for her
My girlfriend started to act strangely due to the stress of this, she started to snap at kids more and said that she felt really angry for no reason, she also started to get headaches and said that she felt Closter phobic! It was also causing me a lot of stress also with her sister saying that I was controlling her!
About month of this and my girlfriend seemed to become very ill, she looked exhausted and could barely keep her eyes open and she had a vacant look in her eyes! I even said to her that she needs to go the doctors. She even the one day just sat there staring at her hands for ages, I kept asking if she was ok and just kept saying I am fine!
Then she came out of that it was like she was a different person, she blamed me for not being there when she fell and that she needed to make herself stronger as she had relayed on me to much! She started saying things like I don’t talk to her, don’t kiss her when I come home from work and said that I just walk out the room when the kids are there! She started to remember things differently and in a way that made me out to be a monster! But in-between all of this she would be herself for a moment and tell me how much she loved me. During all of this she seemed the happiest I have seen her, she stared to contact people she had not spoken to in a while and started to go out more, she even made the suggestion that I should move back out as it would be the best thing for us and that we should not bother getting married anymore even suggested taking the engagement ring off! All of this was very upsetting for me, which she did not understand. She started coming home from work and blasting music and dancing around, if I tried to turn it down or off I was met with a “why are trying to ruin my fun”. She became very cold towards me and would say nasty remarks which was not true, but all the while saying how happy she was and excited she felt. She talked about the things she was going to do in the future and none of which was to do with us, even going on about being single and going on cruises! In between all of this there was moments when she was herself and would cry and say I don’t understand what’s going on and that she loved me and would hold onto me tightly and then change again! I felt like I was losing my mind to which she would say was the case at times!! Every conversation we had got heated and I would get the blame, I was really nervous to be around her. She even stopped eating and would be nearly be sick every time I tried to get her to eat just like when she was fourteen! The last time I spoke her she had 2 stone in 2 months!! She also told me have she thinks about suicide on weekly basis and nearly did when she “fell”
She then began to have what I can only assume are flash backs where our two youngest where playing up stairs to which she ran up shouting “what is going on up here” she came down with this frantic look on her face and I said do you think my daughter was hurting yours? To which she said , you never know!! Another time we both had our youngest again and they dressed up in fancy dress, my daughter had no pants on to which she completely freaked out! When they went to bed she started freaking out about them being in the same bed, so I went upstairs and my daughter to get in a different bed. When I got back downstairs my girlfriend said, what have you just done? I explained what I had did and why to which she had recollection off and started to get mad at me!!
I then went to my mom’s for a week to take a break (her suggestion) and she was very cold still, when I went to see her she said that she has to let me go!! She said something has gone wrong in her head and what she felt before has gone!! Then she started crying and telling me that she does love me!! She asked me to stay the night which was horrible knowing that I would have say goodbye in the morning! She said lets watch a film and order some Chinese like nothing was wrong! We went to bed that night and had sex, which she cried her eyes out after. I stayed with her but could not sleep, we just held onto each other all night! In the morning she was different again, like what was happening was not real! I was in pieces and she said I can’t stand to see you like this, I did not think that you would be that bothered!! I said I have just lost everything, you, my home, my family that I had! She just looked blankly at me! She got the kids ready and gave me hug and said speak to you soon!! All of this happened within four weeks, what she had been trying to build she just tore it down in that time!
We spoke after by text but nothing meaningful, after a while I decided I need to stop contacting her as my own mental health had taken a severe battering! I researched mental health and depression since we split which was ten weeks ago!
Sorry it was so long, my question is do you think that she has Bipolar and that she had a manic episode?
If so when she hits depression will she remember all that she wanted and felt before? This breaks my heart the most to think that she will realise what she has ruined

She really needs an evaluation. It could be so many things not excluding bipolar -mixed episode. If depression hits she will not only blame herself for everything and more. Please if you're still involved with her suggest couple 's therapy.

Honestly, that kind of sounds like my mom. My mom would go on these really strange moods and treat us horribly, she even accused my dad once of being inappropriate with me which is something he would never do. After I brought this up to her, she denied it, and she still denies it to this day - basically trying to make me think I made that up all on my own. I don't know what mental disorder this is, but its definitely a toxic one. The real victims here are the children, because they have to grow up with a mother like that which is extremely difficult. So if at all possible, don't subject your kids to a woman like that. You sound like a good guy, so go find yourself a woman who is more stable. A person like her needs some serious help and often times they don't get the help they need because they refuse it.