He cheated on me (?)

So my bf and I have been arguing a lot for about a week, now yesterday my friend messaged me saying things that she can’t do this anymore and she needs to tell me what he’s doing, she said he’s been asking her to send him pictures (it happened like a few times in the past few days) and before we even started arguing he’s been complimenting her a lot and telling her how much she means to himself and that type of stuff. They’d always just talk on Snapchat so he’d have a cheap excuse that he just doesn’t save the messages on Snapchat (if they talked on messenger he’d have to delete them lol). Anyway, he’d also tell her no to tell me anything, she only showed me 2 screenshots

I’m beyond heartbroken because in my last relationship another girl was involved too, and I knew they were talking a lot to each other I just didn’t know in that way, he’d always promise there’s nothing between them. I dumbed him but didn’t say everything I wanted to, I feel like messaging him telling how he doesn’t deserve shit but then I don’t want to ever talk to him again...should I just leave it and ache in silence or tell him what I think?