Worried

Hi ladies. My fiancé and I have been together a few years. When we first got together he told me about this ex and how she had cheated on him their entire relationship and was actually in a second relationship. she lived the next state over and they met at work, so when he broke up with her he was happy he’d really never see her again. Anyway he’d told me how the break up almost ruined him, he was drinking a lot it almost cost him his job. So we’re getting married trying to be healthy and last night we’re on the couch and he gets really weird and he explains to me that there’s a student observing at his job (he’s a paramedic) and it’s the same first initial and last name as her. (It’s super uncommon) and he reaches out to an old friend to see if she’s back in school and yes she is. So we’re talking about it a little bit and he told me I don’t want you to think these feelings are because there’s not I just don’t know how to feel about her being around. Now my fiancé is a preceptor so once she gets to doing his truck time she may end up with him. I’m just worried because it took such an emotional toll on him and we’re in a great place that even seeing her could make him feel all the negative things again. He’s struggled since his cousin passed away via suicide and he’s finally gotten all mental health things under check and we’ve cut out drinking mostly and are just trying to be happy and healthy. Is there anything I can help with ?