My (31F) boyfriend (33M) of 6 years always talking to ex and I finally read their convo

I (31f) have been dating my bf (33m) for almost 6 years. I have never gone through his phone until this morning. It was initially to look at pictures we took the night before. I also went on his Facebook messenger to see if he was still talking to his ex as this has been a point of contention for a while. Initially he said they were just friends but I thought something else was up and I found out they used to be friends with benefits after asking more about their relationship – she wanted to date him but he didn't want to date her and treated her poorly. Anyways, after finding that out about 2 years ago I told him it was inappropriate for them to talk live! that often and about everything and said it was disrespectful to me (but obviously wouldn't forbid him from it). Well, they're still talking all of the time despite how I said it makes me feel. This morning I decided to search my name in their convo.. I had been thinking he was going to propose and they seem to talk about everything under the sun, but what I read really upset me. She asked him if he was going to propose last year and he basically laughed at it. He also said that staying at my place for a month was bad and he didn't know how we would on-line together (he lives with his parents still..). He said a lot of things bug him about me including how I treat my cat and how I'm going to be a helicopter mom with "her kid". 2,3,4 years ago he kept saying our relationship wasn't great and we might break up. On top of that he would tell her things I told him about my family or things that happened in my life, and it just seems like such an invasion of privacy and disrespectful in general. Also when they met up with a group of friends they said "don't tell me" even though she was with her then boyfriend. Meanwhile I don't talk to any of my exes and cut them out of my life after we broke up. I know I shouldn't have gone through his phone but the reasoning was innocent enough (which doesn't make it okay). I only saw the things that had my name in it. How should I bring this up, or should I at all?