I hate to see my ex girlfriend hanging out with my ex best friend
Why do you hate to see them hanging out?
It's like they are evil twins trying to hurt me
If they are hanging out and they are both exes, then you should just leave them alone. There is no reason to worry about them both if they are out of your life.
Why don't you be honest?
I am being honest with you. There is no reason to worry about these people if you are not consorting with them anymore.