just make it up with her. if she sees you making the move, she might apologise as well
Yes, you should give not just herself some space and time to calm down, but also yourself. It may not always be your best friend's fault in a fight, but sometimes maybe your own.
try to cheer her up with something see likes. You might want to talk over it and tell her you where wrong (even if it was his/her fault.) I get into many fights with my best friend but we get over it:)
no because just because your best freind is a fight doesnt mean you have the ability to back them up but i would cuz it would be cool but people are different. no because if my friend got into a fight i wouldnt get in the fight even though thats my friend because thats her problem and you could get hit or her friend might jump in so no you werent wrong
no
challenge him
no if their your true friend your not supposed to
Nothing it's not your fault
Say it was your fault. swallow your pride what ever " Nothing" means
The only thing you can do is just move on if he cheated on you with your best friend. Don't be mad at her, it's not her fault. It is his fault he was not a true boyfriend after all.
Tell him/her that you want to be friends again. Not that hard.
Apologize. The end.
Find a new friend who's fun. Or really think about what the fight was about, and come up with a solution.