I told my guy of two years his shorts were inappropriate. He comes back with I'm vain and shallow. Now what?

I've tried nicely, discreetly, to get him more stylish clothes. He had better shorts to wear, but he insisted on wearing the raggedy basketball shorts on a day outing with me. The worst part was they were the same shorts he wore to bed the night before. I don't believe I was being vain or shallow, just a little grossed out. So how do I handle the aftermath of his hurt pride and the insults he lashed out with.