Move on from past relationships

I was with my ex since i was like 14 til a little before i turned 20. Now im 22 & i have a great boyfriend which I've been with 2 years but I've noticed that i haven't completed let go of my past relationship that hurt me so bad. My ex used to talk to girls from his past or ex's behind my back, i feel like i stayed paranoid with that & i feel like my current boyfriend is always hiding something from me or that he talks to someone from his past without me knowing. I'm conscious that I'm in the wrong & more cause he hasn't gave me reasons but idk how to act or stop thinking that way. It's not enough to just tell myself "he hasn't failed you". I guess since my past relationship made me think so low of myself i think no one will ever love me, not truly or honestly & i just avoid pain like that the most i can. It's like now i focus more on not getting hurt by a guy rather than enjoying the relationship..