That's pretty sad. I have both my legs and I can't skate... But you... You have one and can skate better than a large percent of people. Don't be upset. Assholes exist and there's nothing anyone can do (except kill them in their sleep... what? nothing).
RANDOM QUESTIONS ENSUE (scroll)
1) Were you born with a missing leg, or did you lose it in an accident?
2) What did they say? People shit talk you on forums and stuff all the time and you never seem to mind.