Friends with benefits

Okay soo me and this guy had sort of a past where we would be off and on all the time because he would get back with his ex.. but today we both decided that since he’s not dating her anymore but might be soon that we should try friends with benefits. I’m perfectly fine with it because I don’t have feelings for him anymore.. but at the same time I don’t want him to get back with her because then my dick appointments will be gone lol... he’s says it’s the best sex he has ever have.. and like we see each other everyday because he lives on my floor.. what do I do in this situation...