I agree with you to a point moon. The best way to handle it is to convince yourself it does not matter. Yes guys can and do think like you describe, but they can also get over it. Put her in your position. Does she want to meet all the gals you danced with? Probably not when put in those terms.
I went to my reunion alone because my wife was too self conscious to be "judged" by people she had never met. I met some old friends and had a generally good time. We both went across the country to hers (mine was local) and stayed with an old friend and his wife. We had a great time at the party, and the whole visit was great. I guess the point is that you can make it as fun as you want to, and why not?
As a side note, let me say that her ex was living in the same apartment building as we were for a while and I don't know what he was thinking, but I was thinking "you're an idiot for screwing up, and I am in heaven." He kept a good distance, and never said a word.