what to do

So yeah.
I'm here today to speak about my boyfriend/ fiances (for future reference ill just call him my fiance) best friend.
Well call him the enemy.
He's charming. He's good looking. He's funny. He's evil.
There were times that me and my fiance were apart, not split up, just in different rooms, where the enemy would make moves on me.
he's my fiance's BEST FRIEND!
and he makes moves on me
He tells me that my fiance will never be able to satisfy me.
That he will always be apathetic to me and that only HE can be right for me.
That's not all. The enemy has a GIRLFRIEND while he does all of this.
So in summary, my fiance's TAKEN best friend is making moves on me. Constantly.
Now you all know me. I'm completely antifeminist. I dont like to make accusations about men. But I don't understand how someone could do something so heartless.
I mostly blame it on sex. Sex drives people to do horrible things, and this is one of the best examples.
Yes im still a virgin *pause for slight applause* and i plan to stay that way.
But the enemy thinks that im well...fresh meat. As SOME men do.
It hurts me, even with my masochism, to be so helpless and feel like I'm this man's little project. Does anyone know what I should say to him?
Oh btw my fiance KNOWS ive told him and they're still friends.
xoxo