Most Helpful Guy
From a guy's perspective, this could look pretty bad to your ex, but I totally get that feeling, that the person you liked wasn't there as much as you may have wanted.
The best thing to do, and this is just my opinion, so don't take it as the ultimate way to go about this business, is to make it clear to your ex that you've moved on. If you haven't yet, telling him now would be the best thing to do to avoid having things get worse. If your new boyfriend treats you the way your ex couldn't, then there's no reason to go back to him, especially if you "love" your new boyfriend. If your ex can't get with the program, it's very unfortunate, but relationships are a learning process in a way, so he'll hopefully get something out of it.
Try to keep things cool and diplomatic, but make it clear that you have specific wants and needs that he simply wasn't willing to provide for you. Of course, it's more complicated than that, but I hope that helps.