Make my ex boyfriend/current friend with benefits into an open relationship?

I don't believe in love (partially because my father moved as far away from me as he could possibly get, and the only aspects of love I grew up seeing was my mother crying over man after man, and when she finally found the right one, he died). In a way, this makes me self sufficient, and I never trust anybody but myself, because I learned in time that people always disappoint you. I can't trust, so I can't love, which isn't so bad, because I hate belonging to just one person or being obligated to anybody. But somehow I'm absolutely crazy about this guy, and I hate that he has that kind of power over me. He's walked all over me, too. He cheated on me twice, but I took him back, cause he was honest about it, and he spent the rest of our relationship playing mind games (He feels it gives him power, he's really just a weak little boy inside). Being like me, scared shitless of getting attached, he kept pushing me away till I broke it off, on which occasion he said that he never loved me, and probably never would, and that our relationship was purely for sex (Not true, I slept with him only after 3 months of the relationship, and every time I broke it off during that time, he'd beg for me back). So now we're friends with benefits. I know how it sounds, but he's not a complete asshole, I know he still cares about me, but if he asks for me back then he's the weak one. I don't even want him back, just an open relationship. We don't need to be in love or anything, just enjoy each others company without having to own each other but also without hiding.

I'd really appreciate any help figuring out what I should do, sorry if it's so long to read!Make my ex boyfriend/current friend with benefits into an open relationship?
If open relationships work out at all - which isn't often - it's because the parties involved trust each other absolutely and communicate honestly. You can't even handle an ordinary relationship with this guy because you're afraid of mind games and power struggles; how is throwing other people into the dynamic going to improve things? Either stick to the ';just sex'; agreement you've already got, or stop hanging on to someone who only reinforces your view that all relationships are dysfunctional and get back to a state of real independence.