I'm going to break up my best friend and his gf
Why would you want your best friend to break up with his girlfriend?
Because I'm unhappy about my past bad relationship.
If you are wanting your friend to break up because you have personally had a hard time with relationships, you are profoundly misguided. It is selfish and inconsiderate to project your own relationship problems onto your friend.
Well now you are talking complete nonsense and nothing makes sense. I'm going to break them up.
What do you expect to accomplish by this? They'll likely see through your Iago-wannbe ruse and permanently reject you. You need to take a long, hard look at yourself; discussing your destructive desires and past relationship failures with a therapist would benefit you.