First of all, who are the trashy acting people in that situation? NOT you!
Perhaps practice some responses to the shunning. Maybe think about how would you like to respond and mentally go over it and maybe even "practice." It couldn't hurt! Over time, hopefully you will see that you can refuse to give them permission to "make" you feel like anything. You can, with practice, gain control over your feelings in a way that does not let their immature and outright bad behavior hurt you.
Good luck. You may have felt like "trash/worthless" but the people who were shunning you were the ones who were the real "trash(y)/worthless" ones -- based on their horrible, inhumane behavior.