Should I leave him now before I get hurt?

I met this guy at my job and its been always fun with him. We have the same humor, like the same things. He’s almost like the male version of me lol. After three weeks of getting to know eachother and having dates wich was always been nice we started a relationship. The thing thats bothering me is the fact that he has a best friend ( a girl ) wich to me is totally fine BUT she was once intimate with her. They started this “friends with benefits” kind of thing after they both got out of a longterm relationship because they both needed “company”. But there was a point that he started to get feelings for her but they decided to not start a relationship to not ruin their friendship, wich to me was weird because being intimate wich eachother kind of already fucked up the friendship they had. The friends with benefits thing went on for 6 months or so. When me and him were getting to know eachother they still had that thing going on but when it was getting a serious between us i assumed they quit. He promised me that there is nothing going on with him and her, at least not the way i think. And that there is no mutual interest in having a relationship with her or whatsoever. He promised i dont have to worry because he's focus is on me. But honestly the thought of it is driving me insane. Im trying to stay chill about it but whenever he’s not answering for hours im always asuming he’s with her. I dont wanna be the kind of girl who’s gonna tell a guy to not see his best friend anymore but its breaking me and i feel like its kind of disrespectfull of him to tell me to just try and accept it... i dont know is this relationship worth trying?

ps: we dont work together anymore. I moved back to my dorm cause of school.
Should I leave him now before I get hurt?
Add Opinion