What should I do about my boyfriend constantly picking on my appearance?

On one hand, I acknowledge that I have an ugly nose. It's misshapen and big. But on the other hand, I resent him for constantly harping on a trait that I have no control over. We've been together for 9 months. His picking on me is slightly recent. I mean, I can't afford plastic surgery and I don't know if its worth the risk but that's beside the point! I really don't know how to react to this. Advice/suggestions?