Abusive ex and flash backs HELP

Ok so when I was 14 I dated a guy who was violent he was 18 at the time he used to lock me up and sexually and physically abuse me luckily I got out of the relationship but now I'm 18 and with the love of my life but keep having flash backs of him hurting me and I'm scared it's going to happen again I know my new boyfriend wouldn't hurt me but the thought is still there and I feel Aweful please help me I'm loosing my mind 😢