Sorry to hear about your experience OP. Sounds like the ride leader was a real dickhead in need of an atitude adjustment.
Last "group ride" I was on was w/ some mtb'ers in Manhattan. I told them I was a noob so they took it easy on me and waited for me when I fell behind. Of course, they didn't tell me when we went from the beginner trail to the intermediate trail, but that's probably cuz I was too far behind. Great guys and made me feel welcome. They seemed happy to see a new face.