I'm with happy, could you give us some examples of where you think you were a douchebag or where somebody other than your ex also implied that you were? Not to discount what your ex said but a larger N is usually better.
I don't see ENFPs as being douchebags or cold and disinterested. You could certainly be melancholy sometimes, that should be okay for anyone. ENFPs also tend to get carried away in talking about a cause they feel strongly about and thus may come across as a douchebag in a "not willing to listen" to any other opinions kind of way. That's the worst I can think of.
The same has happend to me or at least I think it did. I went to lunch with a couple of friends and in an effort to not be such a motormouth I didnt comment to every little thing they said. I was silent. Then, out of no where they asked me if something was wrong... I guess i looked down or something. I thought it was weird because my mood was sort of... calm at the time.