BF advice

So my bf and I have been dating for 7 months and before we started dating he went on a date with this girl. We all go to the same university so she was in his class last semester. I was uncomfortable knowing that they’ve liked each other before but he said that they were just friends in school and he wouldn’t talk to her after school was out. So over the summer, they still text and snapchat which bothered me but I try to not say anything.

So now, we’re back at school and of course, he has class with this girl. I should mention that she had a boyfriend after they went on their date but she cheated on that boy multiple times.

I REALLY don’t trust this girl but he says i’m not being fair to him, which i know is also true.

Every time I mention it he sticks up for being friends with her and really seems like he doesn’t want to let her go which also bothers me.

So do I just go about and pretend that it doesn’t make me uncomfortable?

or ask if he thinks we should break up?