Why not just go to your reunion, have some fun, and let "his" mind do the work for you. When he see`s you he will obviously feel uncomfortable. You might even want to walk up and say something like "hello, remember me ?",. Chances are he will be kissing your ass the rest of the evening.
I graduated at 5-5, #120. I was a wrestler who always was dieting and kept my weight down. I was very popular, but I was everybodys "little friend". So needless to say, my sex life was absent.
I attended my 10 yr reunion and was 5-9, 200 and it was a different story, all the good looking girls got fat and the Olive Oil looking ones were looking good. I have my 20 yr in july and have put on 20 more since. It is a great feeling to see what everyone looks like because it makes all the hard work we put into our bodies worth it.