Hi loliamwithoutwords, well the situation wasn't good at all even up until you got to the point of "is constantly touching me when my boyfriend is not in the room"!!!. There's no way you should be letting this ride and having to put up with this.
Hvert is absolutely right, you need to talk to your fiance, and if he's not prepared to believe you and put a stop to it then he isn't giving you anywhere near the respect you deserve, and do you really want to be with a guy, possibly spend the rest of your life with a guy, like that who will allow that to happen to you/overlook it???
But let's say that your fiance finds it completely unacceptable (which it is!!) and deals with it which he might well do, who knows if it is possible for this other guy to still be doing work/hanging out with your fiance...........but if it is, you need to agree some clear boundaries with your fiance as to when he's going to be around and under what circumstances. If your fiance really loves and respects you I'd expect him to be sensitive to your feelings about this.

Alison