Trust issues

So my boyfriend and I have been together off and on for 9 months. I found out last nigh lt he was talking to another girl for a few days and I called him out. I was crying and a mess or whatever and he admitted to it but we didn’t break up. I don’t trust him anymore and I told him that it’s going to take a lot for me to trust him again. I don’t like feeling this was but I love him more than ever. When I called him out he didn’t show any emotion but disappointment. He’s bipolar so I understand kind of I just need advice on what I should do.