trust!!

I trust my bf but at the same time it's kind of hard to cuz when we first got together in 2013 he strted talkin to his ex for like 6 months til I told him that I was gonna leave if he kept talking to her cuz I wasn't allowed to talk to anyone. I'm still scared that he's gonna talk to her again. but he hasn't in almost 2 years. & his mom is always telling him stuff about her. should I trust him or should I be worried? I need opinions cuz it ruining our relationship cuz I'm always worrying if he's gonna talk to her.