I'm scared I'm going to get used for sex?

So my ex boyfriend we dated for a year I really fell deep for him, let me just say that relationship was so horrible and so toxic. Anyways, skip to the part every time he would break up with me he would tell me I don't care I already got what I wanted anyways meaning the sex obviously (I'm 18). Now I moved on but I'm so afraid I had dated two guys who were long term relationships the first one left me for his ex and this one that I'm talking about cheated on me three times and didn't tell me until I was already leaving him because of bruises. I told myself not all guys are the same but this last relationship really destroyed me when I feel myself getting attached I feel afraid like I want to back out I told this guy I didn't want sex and said he respected my word but it's so hard trusting again what do I do?