My bf drunk called another girl

So me and my bf of 3 years have been on and off. He’s got anger issues, binge drinking, and I think he’s bipolar. He goes through spells of “I love you I’m gonna marry you” to “I don’t see a future with you”. ANYWAYS

Last time we broke up he went to go hang out with friends. He texted me he wanted to break up so I said okay as I was already with a friend. He called me a little later and said I love you I’ll still take you to dinner tomorrow as I promised. I said okay let me know if you need a ride from wherever (they were drinking). They go to a party so I texted him as I was about to head home asking if I needed to take him home. He said no. Later on I asked if there was any girls there. On Snapchat I see more girls than what he said so I said okay why’d you lie. He got drunk and started ignoring me. Then he posted a picture with some girl. (We had just gotten into an argument about why he’d never take a picture with me).

The next day I hear from his friends he drunk called a girl who now goes to college in a different state saying he wanted to “suck her nipples”. His friends say he’s “obsessed with her”. She used to be the topic of very many arguments when they would party together during break ups, discuss our relationship issues, and he wouldn’t let her go as a “friend”. (THEY HAD JUST RECENTLY BECOME FRIENDS DURING OUR BREAKUP). He’s hung out with her alone, laid in her bed....

What do I do. He’s apologized many times, says he’s done drinking, says he’ll see a doctor, he’ll change, blocked her. But I’m worried we’ll break up and he’ll do it again. Or that his friends are right and he has feelings for her.