Shoved out naked

I was about to have sex with a girl I had been seeing for awhile. We were in the stairwell of an insurance building downtown where we both worked. We had removed our clothes and she had me turn around for some reason and then I felt two palms shove me through the exit door and into the the alley between two buildings. I tried to get back in but she had closed the door. I slammed my fists against the door and asked her to open it, thinking she was just kidding around. That's when her voice through the door told me she was serious.

"I know you've been having set with Kathy. You bastard. Fuck you."

Nothing I said could get her to open the door and I knew I was going to get into big trouble if caught like this. The alley was greasy to my bare feet. I looked down both exits from the alley and watched people in suites and dresses move along the sidewalk in both directions, but never glancing my way. I stepped on trash and paper items to get beside an overfilled garbage dumpster. I crouched down feeling **** and alone. I was lucky it was summer but the alley's shadow allowed a cool breeze to chill my naked body. What was I going to do?