If you cant trust somone, should you just let them go?

my ex and i are trying to work things out and get back together. But i STILL do not trust him. he broke up with me, but i thought he cheated on me right before we broke up with this girl. then 2 months after we broke up they started dating. i had no evidence he cheated, i just get jealous. he swears up and down he didnt.. this was about a year ago so im trying to let it go... but still he does other things. like when were sitting/laying beside each other he turns his phone so i cant see what hes texting.. i know he hangs out with other girls a lot and it gets me paranoid. were not together like i said, and he tells me he kisses other girls but thats all. i know its different with me and he acutually loves me but i just can't trust him. is that enough to let him go ? would you ever be with someone you couldnt trust. have you and did it work out? how do you even "work on trust issues" ? thanks..