What if my friend is dating my ex?

When my friend that im going to be taliking about said that he knew I like his girlfriend(my Ex now) he said he was going to brake up with her any way
When they broke up a week later I asked her out 2 months after be broke up...
now hes going back out with her and im kinda mad cause hes shoving it in my face like hahaha I got her!!!

WHAT SHOULD I DO!!!

you should already know that is not cool, LET HIM KNOW. because first off. WAIT LET DEM BOTH KNOW. because that is against all rules of friendship, lol, we learned dis in the like 4th grade when bobby dated courtney! :]

Nothing...

YOU SHOULD NEVER DATE YOUR FRIEND'S EX

THATS HORRIBLE! AND YOU GUYS ARE STILL FRIENDS??? OMG THATS SOOO MEAN!!! I CANT BELEIVE SOMEONE WOULD DO SOMETHING LIKE THAT ESPECIALLY NOT YOUR friend. ITS ONLY OK TO DATE YOUR FRIENDS OK WITH IT AND HE OR SHE IS OVER THAT PERSON. AND APPARENTLY YOUR NOT OVER YOUR EX SO THAT MEANS HE IS MEEEAAAN!!! IF HE WAS A GOOD FRIEND HE WOULDNT BE DOING SOMETHING LIKE THIS TO YOU.