The boy who fucked my best friend

So I broke it off with this guy I had been with because he fucked my best friend literally right in front of me. Like he still thinks we’re friends and I don’t even want to talk to him anymore bc always seeing his face on Snapchat just reminds me of everything he did to me . . . all the time. There’s still so much I want to tell him before I completely cut him off but he isn’t getting the hints that we need to have a talk. And I’m not the kind of person to bluntly start pouring my heart out. What do I do? Do I just cut him off now, despite the fact that I have all this stuff bottled up inside :/