I had sex with my girlfriends mom, how do i tell my girlfriend this?

Answer 1

Counseling all the way around, you no longer have a girlfiend and you need to drop the old girl, nothing good can come of it, at this point. Tell who you want, the damage is already done.

Answer 2

...your kinda screwed with that one...you can either not tell her and live with the fact that your lieing to her, or be truthful with her witch will either make her like you more, or end with her hating you and her mom