Advice about friends with benefits?

I was in a friends with benefits situation recently, he spent a few months pursuing me sending weekly messages. We hooked up and been seeing each other on and off for months. I tried to distance myself from him a few times silently going away due to not being treated well with him contacting me why he was unfriended. I tried to explain a few times that things he was doing wasn't nice. He was obsessed with my ex who he constantly brought up, was talking about me to his best friend telling me they were discussing I wasn't happy and should have left my ex along time ago and then told me about this conversation. To much hot and cold behaviour from him as well and the lies he tells and the future fake. I went into it as a casual thing not with expectations, I even encouraged him to meet other people and when I asked he said he wasn't seeing anyone else but found out he was lying, as we weren't using protection yes stupid I know so It blew up the other night his words were I'm not doing this all the time bye. I always thought casual friends with benefits thing was supposed to be about honesty, no feelings involved but unfortunately I did get feelings or maybe I'm angry I was duped into getting feelings for him. My question is are friends with benefits supposed to be hot and cold, into personal life, talking about beating up my ex etc?

Advice about friends with benefits?
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