OMG! I can't believe that group treated you that way! So not cool! What jerks!

First and foremost, stop riding with that group. When I started riding, I had one good riding partner, who was more advanced than me and very patient, to show me the ropes and set me on my way. He was so great that within 4 months I was riding intermediate trails at Mammoth! There is no way I could have progressed that quickly had I gone with a group.

What also helped was Brian Lopes' book, Mastering Mountain Bike Skills http://www.amazon.com/Mastering-Moun.../dp/0736083715 . I learn well from books, so it worked great for me. It's readable, humorous, and has lots of diagrams. (In case you don't know who Brian Lopes is, he's a pro downhill racer who has been competing for over 20 years, and still kicks the arses of guys half his age!).

I've also learned quite a bit from this site:
http://www.bikeskills.com/blog/?page_id=422
I used it for help with learning how to jump, the advantages of pumping, and improving my switchback skills (which I still struggle with).

Don't give up! You just need better riding partners