I completely understand this so much. Its crazy.
- I fell in love with my best friend a while ago, completely loved him but never told him thinking it would ruin our friendship and make things complicated when he didn't like me back.
- I fell in love with my now girlfriend (his other bestfriend)
- He told me how he always felt
- I told him it was mutual
- Le girlfriend found out and its completely ruined her friendship with him and its messing with our relationship.

Wait it out definetley. You don't want to be the reason their relationship is a disaster and be the cause of pain and confusion for this guy. Things will work out in the end... or at least thats what I keep telling myself. Telling him now would cause alot of pain for everyone.

Best of luck though