Angel,
Is it a 10 year reunion or a 5 year reunion? I have a 10 year reunion for highschool this year but we did have a 5 year reunion which I went to. At 5 years though, it was basically like highschool. My group of best friends of about 7 have been best friends since grade school and all went to highschool together, and were still best friends which is very unusual. Thing is, in highschool there were all these groups socially. My group was probably the largest, but we were inclusive and never excluded anyone. At the 5 year reunion, trying to talk to some people in those "other groups" was nearly impossible. I had several people say "HI" and then turned around. Basically what happened was, everyone spent most of their time talking to their friends now and back in highschool and no one made any real attempts to talk to people that were just aqaintences or in those "other groups" except my friends and I. We only had 115 people in my class. Perhaps the 10 year reunion will be different. Of course all my best friends will be there whom I see every weekend anyways plus around 20 others who I still see from time to time at bars and clubs around town. Its the other 70 people that might be unsocial still. I spent most of the 5 year reunion trying to talk to these other people and had very mixed results. I'll probably go to my 10 year reunion though, but I just hope it does not turn into the 5 year reunion where people just spent the night talking to only their best friends. I see my best friends every week so from my perspective its about talking to those people you have not seen in years.
Your situation is very different since you do not talk to anyone from highschool anymore at all. If you go, be prepared for anything and hope that most have grown up at least a little. There will also be a few who will attempt to compare and contrast everything you have done to what they have done sort of in an upmanship way. If its a 10 year reunion, the chance of things going well is better, with a five year reunion get ready for a highschool flashback.