[MF] Fucking my bar manager on my first shift as a bartender

This is my first story posted. I have a few more to share from my past, but this one is only a couple of days old, and i needed to anonymously tell someone. Throwaway account for obvious reasons. Read to the end before you judge too hard. I know, cheating is bad, and I’m an asshole who could’ve said no at any time

I’m 30 M, just started a new job at a local small town bar part time to help make ends me. My live-in girlfriend also works there part time. We’re both in healthcare. I work 24-48 hours shifts, and GF works nights at a hospital.

My first shift was about a week ago and I was being trained under the bar manager, who we’ll call B. B is 5’4″ blonde blue eyes. Not skinny but not thick either. B cups and an ass to die for. Now I’ve been a regular patron of this bar for about 6 months and know B very well. There has never been a hint of sexual tension between us, nor have I ever viewed her in a sexual light. She was always just a mutual friend of my GF and I. I guess I can describe myself her. I’m 5’10” about 180 lbs. Not athletic, but not overweight either. I’m 6.5-7″ on a good day, average girth.