I think it's best to try to let it go. And here's why: Normally, I would say, "Just message him and make it funny/light. Say something like, "Remember when you said I was socially awkward? Well, today you would have been surprised to see me _______(fill in the blank).
However, I say to let it go because what could happen is he could come back with something equally insensitive, and then you'd be brooding over that. I have problems with this too, so let it end now before you have something new from him to brood over. Get some new interests and focus on that. And double up your exercise, whatever you are doing now.