Most Helpful Guy
i don't think he's jealous but I think the wrongs he feels were done and the fact that you dated him kind of eats at him.
it's kind of like any person you don't like doing something to you, and from that point on you sold of, as you said, hold a grudge against them. it probably bothers him that you dated him and obviously the acts that he feels the guy did to him bother him.
he is trying to put himself above your ex, maybe reiterate how big of (as he sees is) a douche your ex was.
it's fairly immature assuming he's close in age to you, but also a pretty natural defensive tactic and coping mechanism for something that bothers someone0