7yr partner avoids blame, discards repeatedly

I have been with my fiance for 7 years. She has two teenage daughters who have been like my own since they were 8 and 10 years old, respectively. We were in our twenties when we first got together and so have gone through a lot of challenges and growth together. We both came from homes where our parents fought a lot, mine divorced when I was 9 however, and hers stayed married.
One of the problems has persisted over the years and I am only now recognizing the enormous impact it has had over the years. It is almost impossible for her to accept her share of blame and responsibility for our problems. She is quick to point out my behaviors but becomes very defensive when I am sharing my concerns with her, even taking it very personally when I discuss the girls. And, when I point out my needs or feelings, they are often invalidated. And worst of all, whenever I finally start getting upset for not being heard, there is usually an argument that ends with her angrily breaking up with me, usually calling me some kind of emotional bully or abusive manipulator.
This has gone on for years now, and when it happens, she almost always becomes like a different person. Sometimes very angry and insulting at first, but always cold and unapologetically cruel. She starts to cut off communication, swears she has tried to get away from me for years, brings up the same handful of my mistakes and insecurities and seems to only remember our low points and not the hundreds of days in between that have been so wonderful. Usually, I end up blowing off whatever my concern had been and fighting to save our family. Eventually, she seems to almost snap back from a cold and unfeeling person to the loving and compassionate woman I know her to be. She cries and says she doesn't know why she does this and I forgive her and often look inward for how I can grow and overcome my problematic behavior. I have recently started to see how these breakups have caused her to avoid accepting blame and, while I have had to grow and overcome many of my issues, she has been avoiding most of hers which makes me feel unloved and sounding like a whiny broken record.
She has started therapy about a year ago, and eventually vowed to not get angry and break up with me anymore. However, after a few months, it got much worse. She would get angry but insist that she wasn't and that she was perfectly calm. There was a string of breakups where I would come back depressed and frustrated and soon be thrown out again. She even started to get the girls involved in our conflicts and by showing them only her side, has painted me into an angry monster and turned them against me. I finally told her the breakups and refusal of accountability are abusive and I am not going to allow it anymore. After which, she went into complete denial, called me the abusive one and a master manipulator, she minimized and devalued all that I do as a partner and step-dad and seemingly discarded me for good. I have no allies, the girls seem to hate me, her family is against me I have had to move out of our home and start over.
But, I still love her and can't stand to give up on my family. I have no other family and they mean the world to me. I don't see how she can become so unwilling to consider examining her own behavior and unfeeling as to blame me for everything and leave me feeling hopeless and alone. I have suspected that she may have a personality disorder like Borderline or Narcissism, but most of the time she is very loving, It just seems like when she gets triggered by certain things, Mr.Hyde comes out, and now it seems like Jekyll was the mask the whole time.
I don't know what to do and I have recently started to examine the whole relationship and the huge amounts of damage this behavior has caused and I am complicit in it by allowing it to go on for so long. Anytime I have mentioned these things, she accuses me of trying to convince her she is crazy. And it seems she is starting to get close to the topic with her therapist, which makes me hopeful, but seems to be bringing a lot of chaos to the surface. Should I just escape and give up even though I love her and know this is all wrong or should I keep fighting for my family and be hopeful that she will honestly address the issue with her therapist?

Hello. Welcome to PC. That's a hard call. She is the abusive one and was wrong to put the kids in the middle. It doesn't sound like she's worked out the problem yet in therapy and it might take awhile. The question is can you put up with this behavior while stifling your own needs? After reading your post again, I really think you don't need to go back until she shows substantial change. She has done a lot of damage at your expense. I wish you the best and hope you make a decision that brings you peace.

Welcome to PC. I see this is your first post. The first 5 posts go into a moderated hold, all other posts are automatically released and appear as you post.

It certainly sounds like a heartbreaking conundrum since you've established yourselves as a family unit. She could very well be replaying learned dynamics of her own youth with the push/pull of breaking up/making up. Not the healthiest of choice examples for the children.

It's tough to know if waiting it out for her to have an 'aha' moment is in your best interests or not. The fact that she's in therapy is certainly a step for her. Are you also seeing a therapist of your own?

If there's anything about therapy that I do know, is that there are times where processing it all can be overwhelming and emotionally taxing. Does she also utilize a support group? Sometimes it helps hearing about the therapy process and chatting about it from and with others who are going through it. It's like peeling away at an onion. Layers upon layers, as well as, tears.

Hi trev,

Nice to see you here on PC

What sort of concerns, specifically, do you address her on? What sorts of things do you see as her fair share of the blame?

Somewhere in the middle you two are not meeting half way. If you put aside her lack of "acceptance" of what's going on here, just for now, I'm wondering what the real issues in this relationship are? i.e.: exactly what it is you're trying to get her to acknowledge.

What do you love about her?

Welcome to PC trevortf. Unfortunately you and your fiance have been trapped in the same kind of dysfunction you witnessed growing up. Also, when the parents struggle to get along and accept their own part in whatever goes wrong and get all "self absorbed" in that, the children often suffer, especially when a parent uses the children for a sounding board or expects the children to side with them and be "angry" at the parent that needed their concerns heard.

If your wife has decided to reach out to a therapist that's a start for her where she is admitting she needs "help". I agree with healingme4me in that going through therapy can bring out some confusing emotional challenges where a person can get worse as they are looking at whatever is bothering them that they don't understand. Often this Mr/Mrs Hyde persona is connected to some kind of deep insecurity where a person can be triggered and become very negative towards others. It can definitely be awful when on the receiving end of that anger and resentment. However, somehow this individual learned that when they behave this way they somehow get what they want which is usually "control" or feeling they have the upper hand in the relationship or group. Interestingly enough this is something that all "primates" do so it's not surprising human primates are so susceptible to this behavior too.

It would be very helpful if "you" sought out therapy for yourself so you can learn "why" you go along with these cycles of how things are good for a while and then there is some kind of flare up where you tend to end up in the dog house like you have described. It's important that you learn if you unknowingly accept emotional abuse and learned how to be the codependent without knowing it.