Advice About Revenge....or something else.?

Here's the deal. A long time ago I got involved with this abusive guy. He was emotionally abusive. So recently I began talking to one of his friends that has a mive crush on me( but we're just friends) the abusive guy (my ex) he is going around and defaming my name. Hes not calling me or anything but he's saying im vindictive and everything basically saying im a snake. Its obvious that he thought his friend just wanted to sleep with me then when he found out he really liked me he tried to defame me. He has been wanting to see me for months but I refuse. I think he's mad because of that. I want revenge! What do you think I could do to give him a taste of his own medicine of mess his head up. What about gaining the trust of his best friend?