I don't want to invite my fiancee's friend to our wedding
Why don't you want that friend at your weeding?
She makes me feel like she want to take my finance away from me.
I understand that you might be concerned about his friend but it would be very wrong to leave her out of the wedding if she's is close to your fiance.  You should talk to your partner about it, so that he knows how you feel about that friend, but still allow her to come. If you don't do that your fiance might think that you are trying to control him and pull him away from his circle of friends.
Maybe you're right. Maybe I'm overreacting.
I'm glad you feel that way. Jealousy can be hard to deal with. If your fiance  cares about you, he'll empathize with your feelings, especially when you show share your conflictual feelings about the situation.