What do I do?

I know for a fact I'll probably get called stupid for this and bashed on because let's be honest no one really has respect on here. but last August, (my birthday) for awhile I had a feeling my SO was cheating, well he left his phone in my purse, and so, curiosity got the best of me and i was RIGHT, he was seeing another girl and getting nudes and from other women, and idk why, but I pushed it aside, we've had two miscarriages together and I think thinking of them, is what makes me stay, well anyway, in October, we got in a huge fight and he went to a party, I showed up later that night and when I walked in the house he was flirting with another woman, when he turned around, he instantly acted surprised I was there and tried acting happy, plus he was insanely drunk. I tried to get him to leave with me and he got mad, because I didn't want him to drive home. So I went home and got his mom to drive my car, so I would get his car so he couldn't drive. Well as we were trying to do all this, he hits me and pushes his mom down and then proceeds to threaten to beat me. Well, again, I pushed it aside because God only knows why, and now, we're engaged, and I have a feeling he's seeing another woman, again. Well then this girl messages him, I was holding his phone to take a picture saying how much she loves him and hates that he broke it off with her blah blah blah, well he claims he doesn't know her and someone hacked his stuff...I left it alone...and now I have the feeling again...But I can't prove it. He claims he's not because he doesn't have a lock on his phone and tells me I can go through it if I want, but I don't want too. I've been planning on leaving him, but I have no money, because he's in charge of the money.. And I have no family to go too... I don't know what to do.. I'm so disgusted with my self for staying with him... What do I do ?