I've been with my gf for 8 months and Friday night I took another girl that I had known earlier home. I don't know why I did it, but I feel terrible. My gf is plenty pissed but there's a chance we could stay together. I don't know how Friday night happened but I believe it was a combination of personal problems that in the past few days I have been trying to identify and work on correcting. My question is if I have ruined this relationship for good or if there's a chance to salvage something. I've been communicating with her about these things but I just hurt her so bad I don't know. I couldn't imagine being with anyone but her. What should I do?