I am slightly hesitant to tell you this story becuase I don't want to give you false hope but I will anyway as I hope the key message comes through - that improvements are up to HIM, not you.
DH has never cheated on me (as far as I know). However, he also struggled with anger. Practicalyl from te start, he would occasionally have these massive bursts of anger that were entirely OTT and terrifying. And of course, afterwards, there would always be a bit of gaslighting (it wasn't that bad, but I am sorry) or whatever because of course, he didn't want to admit that HE was the problem. And he was (is) a good man - loving, kind, supportive etc. So I'd let these moments go.
Then one day he had one of these fits of temper over something so incredibly ridiculous and to make matters worse, he did it while driving the car and nearly caused a really bad accident. It was a lightbulb moment for me. And I realised that while he was a good man, I could not be with someone like this because in those moments, his behaviour is NOT that of a good man. It's controlling and abusive and borderline violent. And that over time I would be questioning everything I said or did to prevent an irrational outburst of anger. So I told him the relationship was over if he didn't get help and I went to my sister's house and cried for 3 straight days. Truthfully, I think my sister hoped it would be over.
But he did it. He got help and started therapy THAT week. And he did the work. And it was hard. and it took a long time and he had to relook at everything he thought he knew about himself and his upbringing and his behvaiours.
We have been married now for almost 20 years. Mostly happily (we have our moments
). When DS was about 2, he started backsliding and he threw something one day. I very very calmly told him that I didn't know what was happening but be needed to sort it out, asap. which he did and, in fact, that was really helpful because he was able to share some of what was happening in his head after that and he has never behaved like that again. He still has a temper, of course. But the terrifying anger, the potential for violence, the gaslighting is all completely and totally gone.
But HE HAD TO DO THE WORK. And it's very obvious t me that your DH is not there. So you can tell him it's over unless he sorts it, but you have to have a very tight timeline - he needs to start therapy within weeks - and then stick with it.