It's hard, I'm not very good at this either, but I don't think a long winded "I got you back" sort of comment is the answer. If anything, it might just backfire and give them something else to pick at about you.

Walking away is a good response, but I know how much it burns when people are disrespecting you and you walk away with your tail between your legs.

I've learned from watching a mentor of mine, he was very confident and a huge asshole to everybody. If someone were to disrespect him, he slows down. He lives in the moment very clearly, and and turns his attention toward them in a very menacing way, but it's so subtle. Not enough to make himself look stupid, just enough to make them uncomfortable. Then he acknowledges the insult, and decides how to react.

In a situation like that, he'd agree, sternly, as if saying "Yes, I have found people who are better than you, who treat me with respect.", but all he would say is "Yes" or maybe nothing at all, but it would be implied.

Strength comes from body language, not necessarily from words, and if you can learn to manipulate and control your body language in situations like this, you'll feel much better about yourself.

That's how it's worked for me anyway, I hope that helped somewhat.