So my girlfriend got a massage from a college senior

Okay, to start off, I know massaging is a perfectly respectable business, and a lot of things don’t happen during it, but the thought of my girlfriend being naked and rubbed down by a college senior scares me. We’ve been going out for about 13 months now, and I trust her completely, but I still can’t get over this. I have trust issues, and I do not trust whoever is massaging her, because it is not hard for a college senior to do anything he wants to a vulnerable, naked 15 year old girl who he is already touching. I thought the touching would be something she and I could share, something only we could do together, but now that I know she’s gotten massages, I’ve lost that sense of love and the special moments we have together when we do. I’m very over-protective of her, to the point where I think I irritate her sometimes, because I’m so worrisome of little things she does. And I need more than people telling me to just get over it when it comes to this, because it is a lot easier said than done. She means so much to me and I don’t want any harm or abuse to come to her, I just want her to be safe. Is there anything I can do to get over the fact that I get extremely scared when my girlfriend is naked and rubbed by another guy? Please, I need help…