Have you tried searching with Classmates.com? Or do a free trial of one of the verification sites, such as beenverified.com. I do wish you all the luck in the world. But as has been said before, do try to forgive yourself — otherwise this hurt will never heal.
I do understand your regret quite well. My college roommate was gay and out in 1972. We became good friends, stayed in touch for a few years, but lost track (phone/address changes) when my wife and I moved to LA in 1975. He was murdered in 1977 here in Seattle; I only found out when we moved back in 1978 and tried to look him up.