You're right, clearly I mustn't fully trust him. I am certain he wouldn't do anything intentionally but I'm not certain something accidental won't happen.

I'll have a chat with him tonight and see how it goes. Depending on his response I'll give it some time and lay out a boundary that if she becomes a reoccurring theme in our relationship I'm not interested. It's just difficult because I do work in the same place as him and 100% would have to find a different job haha