FWB issue

I need advice on how to stop having sex with my fwb (friend with benefits) person. The first couple of months, the sex was hot and steamy, even tho he has a small penis, but it's different now. I've already told him we need to stop but he doesn't want too. I know for a fact that he hasn't caught feelings ... it's just sex!

It's hard to avoid him, or to just go cold turkey and stop all communication since we were best friends at one point and. He'll tell me he needs to talk I got over to his apt, or vise versa then end up having sex. I cave in when he surprises me from the back and starts kissing me neck... HELP!