Me and my ex just had a bad break up (he told me many times he had no sexual/romantic interest in a friend of his then broken up with me and immediately started dating her, I'm of course devastated), he wants to stay friends and I don't want to abandon him because he's had so many people abandon him in his life. 

However, I'm so hurt by his actions, and he refuses to acknowledge how badly he's hurt me. He's said "sorry" many times but any discussion I try to have to have ends in him getting defensive and saying he did nothing wrong because he was confused and didn't mean to hurt me, getting mad that I'm not being more understanding of his illness, or just flipping out at me in general (I was always endlessly forgiving of his hurtful behavior when we were together, this is the first time I've stood my ground on being upset with him). I try to point out his hurtful or inconsistent actions so he can be more aware of his actions and work on himself (he says he's started therapy recently, which he had always refused to do when we were together) but he gets so angry and upset every time I just have no idea how to talk to him about any of it. He tells me he said things he never did, or that he never said/did things he absolutely did say/do. We had a huge blow out today when I pointed out he can come off as ungrateful sometimes, citing a few weeks ago when I bought him grocery delivery while he was bed-ridden with the flu (we were long distance) and how he never acknowledged or thanked me, he got mad, swore at me, and said he obviously did thank me. I sent him screenshots of our convo to point out the hadn't (I wasn't trying to be petty I genuinely wanted him to see he hadn't done that and to realize I wasn't just being dramatic/lying to him, especially since this wasn't the first time we've disagreed on past conversations) and he didn't respond for hours then said I was a stranger to him and when I questioned him on that he said I clearly hate him, still without acknowledging his misremembering. I talked him down but I can't keep doing this, it's exhausting and painful for me. I'm incredibly unstable myself right now so I can't keep dealing with his anger and gaslighting. He also started talking about suicide after I stopped responding to this texts for a few days to try and focus on my own well-being, and after I talked him down he told me the following morning he was perfectly fine. That whole situation felt incredibly manipulative and has made me very afraid that kind of manipulation will keep happening, which is so unhealthy for both of us. 

Like I said, I don't want to abandon him, I love him so much but he's been so cruel and insensitive to me something needs to change. Does anyone have any advice for now to broach these conversations with him? Or any other advice?