Male Mind games

I have a partner who I have been with for 2 years we suprisingly expected our first baby and my last as I have to have a hysterectomy after I give birth due to a growth, however not the point I'm asking advice for. We have 5 children two his and three mine.
Mine see their dad and I give him respect even if he is a jerk at times but he is my children's father so jerk or not respect and being nice is what I can do for my daughters. His two kids do not see their mother.
After multiple arguments in the two years we have been together with his daughter being a very full on little girl and needing attention from everyone to survive otherwise breakdown emotional mode happens it's taken some time to adapt as a family, with her attention seeking leading to lies where he sides with her over myself and I'm left distraught over his ability to believe a 9 year old over an adult.
Tonight we have had another argument which lead to double standards of how I have 5 children and he feels he has two and not accepting my children as his in a way as we are a family. The discussion happened infront of his 9 year old girl which I was not inpressed about and lead to him saying things to her such as did you hear that she thinks this which infuriated me more as she's a 9 year old and he needs to pull his head in.
I gave space and spoke to her at bedtime tonight saying I was sorry that the conversation unfolded infront of her and we should have moved on, she mentioned to me that she doesn't like it when he says things like did you hear that to her, she gets upset and shuts off she also mentioned to me that he thinks I hide things in my phone deleting stuff, and she is to call me by my first name now as they have always called me mum, also mentioned that he ranted on about how he supports everyone and he wants to go places and do things but he can't because he has to pay for our house and my stuff as I'm 8months pregnant work is not there.
I told her that no matter what I was not angry at her but angry at him and that I love her she said that her dad is angry all the time and she's seen him angry alot before he was with me. I reassured her that he was a fantastic man and loves her heaps and works hard for all of us to be the best we can. Thinking to myself the whole time this conversation I'm having is not meant to be had as he should've never said any of this to her as she's 9 she needs to be a kid.
I then sat down and spoke to him after this convo and said how I would like it if he could try to let her be a kid and him worry about being a adult. He needs to protect her not the other way and I mentioned how she said about the calling me by my first name and the deleted messages etc. He said to me is she still awake because I never said any of this and lead me to believe that she had fibbed which was common behaviour for her atm due to attention. He said it's all been turned around on him being the bad person and I said so you never said any of this he said no. I said oh how clever of her to think of this maybe we need to stick together and beat her at her own game of lies, I paused and said did you really not say any of it, he said yeh I did....

What am I to believe or do in this situation? has he lied or has she? I feel so stupid. I am unsure whether I can trust him or who to trust. I feel like I should shut off and leave because this has just gone pair shaped quick.
What do I do? Is he a psycho or is she making stuff up? Feeling like my brick wall needs to be thicker to protect myself and my kids right now.

Help!