Hi everyone this is my first post and I think it's going to be a long one so sorry in advance.

Me and my fiance have been together for about a year and a half, I love him with all my heart. We're not perfect people we both have our own issues but as a couple we talk through it and get to the root of the issue and as a team work through it except for now.
Everything was perfect for the first year of our relationship, my family loved him and his family loved me. Families have always been something that worried me in relationships, I suffer from complex PTSD from my childhood and extreme anxiety and depression so meeting future in-laws was a terrifying thought but all of that was washed away when I met them. Everything went perfect, we all hit it off with our sense of humour, I was polite and charming and we all seemed to gel perfectly or so I thought.
Once me and my fiance decided to get our own place is when things went down hill, his family would make the odd rude remark about how small our place was but it all rolled off our backs because me and my fiance loved our first place. After a few months of living there we got a letter stating that the council would be doing an inspection of the property, we figured it was routine and got to scrubbing the place top to bottom. A few days later my fiance's mum had casually told us that she had called the council and reported the place so that we would get kicked out and given a better home, now this woman is smart she knows that that's not what would have happened, we would have been declared homeless and forced to stay with her. I know this because my fiance was technically homeless and living with me for months before getting the place.
I put it down to concern and let it go, we failed the inspection on some minor things that were easily fixed so I figured no harm was done.
A few weeks later my fiance sat me down and showed me the messages he had been getting from his mum, paragraphs of text all saying how abusive and controlling of him I am, how I won't let him see his family anymore I was absolutely stunned. For the record the only reason he sees his mother is because I'm the one telling him too and kicking his butt out of bed to go see her, we live in the same town and see her constantly while we're out and about and have dinner with her once a week, I see my own family less than I see her but once again I let it go, I told myself she was probably having a bad day.
Fast forward to a few weeks ago I was having a really low point in my life, my dog got sick and ran up huge vet bills and my anxiety and depression was high. My mum had come over to visit and I just broke down in tears to her, we decided it would be best if I spent a night with my mum where I didn't have to worry about keeping the house together where I could just relax and be pampered by my mummy, my fiance agreed it was a good idea and that he'd keep the house together while I was gone. As I was walking to my mum's car my fiance's mum pulled in and asked what was going on, I told her it was all just getting a bit too much and that I needed a break, she was sweet as pie and told me to go look after myself. That evening I was facetiming with my fiance and he showed me all the gifts his mother had brought, piles of chocolates and crisps and a new headset that was meant to be for his birthday which was a few weeks away, his mother had even planned to get his hair cut the next day and a family barbeque was planned the day after I told him I was happy for him but deep down all I could think was how much better his life is without me. He asked me when I'd be back and I'd already told him before I left that I wasn't staying more than a night, our dog was on 3 different types of medication and special homemade food and he's never done any of that before I didn't want to put too much pressure on him and to look after the house on top of that. I should have just stayed because when I got back to my home his mother was there and had invited the one person she knows that neither me or her son like in the house. Not only does he do shady business the first time I met him he spoke for hours about how he'd like to bang my sister after that me and my fiance agreed that never again would be come to our home, yet there he was.
I didn't have the energy so I greeted them and just went and chilled on my balcony. They left shortly afterwards and I got some alone time with my fiance, he told me that he didn't know if I was ever coming back, I asked him what on earth would ever make him think that and he just shrugged and then I realized it had been his mother, all the gifts and attention had been her way of getting her claws into him. That evening he told me that his mother was angry at him, I didn't realize but it was actually my fiance that asked them to leave and I've never been more proud of him to stand up like that, I didn't know he had it in him but he got hell for it. He showed me the messages and again there were paragraphs after paragraphs calling me controlling, that I was selfish for leaving him like that, that I'd only came home because I saw how spoiled he'd been and I wanted in on it, that if things didn't change she'd have him committed, that I was mentally ill and that I need serious help. Those were the messages that broke me, because every word she had said was my biggest fear, I grew up being treated like that and to be told I'm doing that to someone broke me. I sat with it for a few days, talked to friends and family and looked at it from all angles and concluded that his mother had serious jealousy or possessive issues with her son. I had got messages from his entire family sending me supportive messages over my "breakdown" so his mother had told everyone I was unstable. He had arranged to meet with her for dinner a few days later and I decided to stay behind, I told him to have fun, stay out as long as he wants I just asked him to promise me he wouldn't talk about me to her and he promised.
And he broke it he came home telling me that everything was fine she wasn't mad at us anymore and we can all just forget about it and move on, but I couldn't just move on this time she had dragged my name through the mud, I told him that what she was doing was abusive but he told me she was just concerned and that I was overreacting, we almost broke up that night. He was so blind to what she was doing but he's lived his life this way it must just be normal for him now. We both agreed that we'd keep contact with her as usual but if she said anything bad about me again he'd squash it there and then.
Things have been weird since then, every time I mention his mum he gets defensive and shuts me out which makes me feel pretty alone in this situation, I'm scared to go spend time with my family incase I get attacked for it again.
At this point I'm just scared at the lengths she'll go and what it'll take for my fiance to put the pieces together and see what's really going on. Hes told me that his mother paid him to break up with his ex when he was younger so it sounds like she's been controlling him and his relationships for a while.
I suppose I mostly just wanted to vent, when I have no one around me but him and his family it's hard to tell if I'm overreacting, it's hard to stay sane. Hopefully in a few weeks I'll be meeting with a therapist, I had hoped that we would be discussing my complex PTSD but this new drama has become the main focus of my life.
If you have any advice on how to cope in this situation it would be greatly appreciated, thank you X