You know you're better than he is. Make a list of why you're better than he is and keep it accessible at all times. Find the thing about him that you couldn't have ever lived with. Here, let me help with an example from my own life:
Mitchell was really not handsome. In a conventional way. Well, not even really handsome in an unconventional way. But I didn't think that mattered. I thought that the old adage was true: "It's what's on the inside that counts." I thought he was beautiful on the inside. Gorgeous. Heartstoppingly, achingly attractive. But I still had to look at his outside and, occasionally, I felt disgusted. I looked at him and thought, "Man, is he lucky to be sleeping with me." I realize now that's probably not the healthiest attitude toward the person you say you're in love with. But he was lucky. I'm in better shape, I'm better-groomed, I have all my hair. I once saw a baby on the train. A funny-looking baby. A baby who looked like Mitchell. Not a baby who looked like Mitchell might have looked as a baby, but a baby who really looked like Mitchell. Like Mitchell does now. And my heart fell. I went out with a squishy, jaundiced, newborn-baby face. But I supressed these feelings in favor of the ones I felt were more meaningful. He listened to me, he thought I was smart, he seemed to understand the intricacies of romantic interaction, he liked my writing, he was laid-back and easy to be with. So what if he looks like a troll?

It matters. Those things matter. Everything you feel matters. And loving someone's looks is as important as loving someone's sense of humor. And it's not about some weird, contrived, conventional, stereotypical standard of beauty. It's about being able to say honestly, "I'm the lucky one."

No good relationship is based on feeling better than your partner. But if the partner in that good relationship dumps you for no reason, feel better. You are better and he's the worst.