Doing that doesn't make you much of a friend. Does he know how little of a friend you really are?
No.
Best friends are best friends because they share similarities. Lazy or hopeless guys love their best friends' girlfriend because he would like the same kind of girl.
you tell him and ask if your really best friends, because best friends should never ignore you
Cheating
That's up to you.
he slept with her because he is not satisfied with you
you should apoligize t your friend and his girlfriend
You're going out with who was previously your best friend.
When you are over 21
Wait until they break up then ask.
No just best friends
Try to trick him or get wasted is what i do