If someone is willing to wallow in the mud, calling names, and making fun of someone just because they're different, well... you just can't be friends with that kind of person. What are they saying about you behind your back? What are they going to say about you if you rub them the wrong way?
Better to just cut ties, and walk on by. Bullies will never be good friends, and if you stand up to them, you're just going to get in a yelling match, until you're both hoarse.
It reminds me of the feminists who go beyond equality and turn into man-hating bigots themselves. Trying to solving a problem by becoming the problem is not going to fix anything at all.