Questions: Guy's Behavior

Now he’s asking me to DM him. Imagine hurting someone and then saying something cringeworthy. I can’t imagine calling a white guy “mayo king” Weird how some people make your ethnicity your whole identity!

Guy I was dating for a bit broke up but said we can be friends. When I told him I don’t want to be friends and was trying to resolve his misunderstanding so he can reconsider his decision to break up, he said few very unkind things to me and then at one point, he looked sad that I didn’t want to stay friends and told me he still talks to his other exes. Should I consider his friendship or just go no contact?

He said months ago that he doesn’t reciprocate my feelings, but recently started flirting back, then backing off, then flirting back…. It’s really messing with my head and I feel like I’m going insane… it needs to stop. Doesn’t help that he’ll cheer me up when I’m down either.
And he’ll respond well to my sexual flirting or carry on conversations about sex… and he’ll be clearly enjoying it, like smiling and blushing and he even once got hard around me…. I dunno… it’s just too much.

do I send him a message saying it’s best we don’t talk anymore? Do I just gradually pull away? What do I do?
also he’s much older than me. I should’ve stopped it a year ago. Weird thing is that he never followed me back on instagram, but he follows everyone else back… but he would sometimes comment on my Facebook posts..