Dating ex's friend?

About 3 months ago, I broke up with my boyfriend of 4 yrs, and in the past week I've gotten with this guy. He's a bit older than my ex, I've known him for 3 years, and he's a mutual friend of me and my ex boyfriend. My ex was abusive emotionally and sexually, cheated on me, and was inredibly manipulative. My current boyfriend resents my ex for what he's done to me. I'm totally happy now with my current boyfriend and we're recovering from depression together. Was this a bad thing to do, or is it okay?