man, I can't believe they would not include you. That is messed up. If it was me (everyone is different of course). I would say how I feel to the whole class and let them know that it is pretty crappy of them to act that way.
Please don't give up man. This should just motivate you even more to make it through.
I just finished school, and was also the only male in the class. There were some disadvantages to it, but it also had it's advantages.
I don't know what to tell you as I don't really know anything about you or the program you're in. All I can say is that you shouldn't let 23 women who don't seem to have concern for you make a life altering decision for you.
When you get to working, you won't have this problem. Their will always be gossip and all that junk, but that's everywhere.
Don't give up yet man. IF I CAN DO IT, YOU CAN DO IT!