Recently got accepted to a grad program of about 60 people. LTR is already in the program and is pretty popular/well liked among other people in program. I've been dating LTR for 1 year and recently with RP help realized she's a pretty shitty LTR. I want to break up with her, but I don't want to start grad school having most of my program hate me when she inevitably bad mouths me to her friends.

Honestly i've been cheating on her with multiple other girls over the last 2 months because I realized things were going to end. I've been thinking of just staying with her until I've met a good number of people in the program so I can establish a reputation before she could ruin it.

Should I stay until I make some friends, or should I leave now and risk starting grad school a few steps back socially?