I agree with Jean-Marcus (great advice)!! I think that that jealousy and distrust put a HUGE strain on a relationship. If you know your FI is "charming" then you need to accept that - he is who he is KWIM? It doesn't mean that you have to like that biatch in his office, but what does it say about your feelings towards FI when you worry about them being together? It says that you don't trust HIM. Don't get me wrong, everyone has jealous moments, its just all in how you handle those emotions.
I understand that you have been hurt in the past, but what does that have to do with FI? Nothing really. If my FI was giving me a hard time about some guy in my office and I had done nothing to make him think I was not trustworthy, I would be pissed! That would be a huge slap in the face to me. Anyhow, no judgement here, I'm just trying to offer the other side to help you work through your feelings. You look radiant and beautiful in your profile pic, and FI loves that about you otherwise he wouldn't be with you. Just remember that!! Good luck and we're here for you!!