ruined my sex life

so, my ex kinda ruined any sexual things for me cause he’s an ass. he cheated on me with a girl (they kissed and flirted while we were together and talked about sex), he watched a lot of porn, talked to girls from CRAIGSLIST ADS and made a sexual tumblr pretending to be a different person and was taking to ANYONE who would message him sexually on there and i honestly just don’t feel comfortable with watching porn or anything anymore. i don’t know what to do. he kinda ruined my sex life and i just feel sick when i watch porn sometimes cause it makes me think of him with other girls. i don’t know what to do at this point. i NEEDDDD help & ways to try to get around this. i just feel like i’m never going to get over this and i don’t know what to do