Ex-best friend

We were the best of friends,what happened to us now?
You chose him over me,you changed but i dont know how.
You told people that I had changed but it was really you.
You were my best friend,you were a guy,we both were to.
He was my ex,you were my friend.
It didnt add up until the end.
When you kissed him,I thought it was wrong.
But now that I think about it,you can stay gone.