How do you handle haters?

I've been growing as a person the past few years. I finally have a strong steady income and time to work on myself.

There seems to be a group of old friends going around trashing me behind my back. Going to my coworkers talking shit about me, telling them to say specific things to me to get under my skin.

I know success brings haters to the fold. What should I do, and how do you guys deal with it?