Most Helpful Guy
If you don't fully trust him, you shouldn't have gotten back with him. Don't get with someone that you already have a tough time trusting. He's going to hurt you again. Usually, I say just dump him and move on, but if you want to give this a shot, tell him he has to earn your trust before you're fully committed. It's up to you to decide whether or not he has done that yet, but make him work for your trust. Tell him it doesn't mean getting you gifts or taking you places. It means that he needs to be show that he is committed to only you, and let him know that it might take a long time before you're able to commit again after what he's done to you. Until he has earned your trust, don't sleep with him, don't go to his family's Thanksgiving or Christmas, tell him not to get a anything big for Christmas, only buy him a card for Christmas and don't at all tell him you love him unless he asks you if you do love him. You said you do still love him so don't lie, but don't bring it up unless he asks. And if he does, you say "yes, I love you, I never stopped, but you hurt me and you need to earn my trust."
And don't be afraid to have one foot out the door. If he doesn't seem like he's going to give a good vibe, tell him it's time to give up. At which point, you two are done with each other for good. You're too young to get wrapped up in relationship drama like this.
Most Helpful Girl
It will always be there in the back of your mind, as they tiny voice of doubt.
But if you really want to give it a go then let him try.
Set up a boundary line for yourself. "If he does ######### then it's over. If he doesn't do ########### I'm out." And stick to it. No fudging the line. No second second chances.
Don't let yourself get set up for a life time of forgiving this behavior or that.