Should I or not try to make contact with an old high school friends?
Things to count into the matter:
1- He was literally the only friend I am, I was far from being popular back then.
2- He grew up to be a solid guy, physically as much as mentally, I saw him at some convention but I didn't dare talk to him then.
3- The only way I can contact him, is by adding/calling his relatives and tell them I'm trying to get in touch.
So is this a good idea none the less? Because it sounds a lot like it's fucked up.
I'm currently not feeling the best of myself, if I got rejected by the only person I felt as a real friend, it would hurt me deeply.
I don't expect him to become my friend again, just so that it is clear, I know he probably moved on and got a lots of people around him now.
Honestly you will have to do the normie thing and follow him on Facebook or any other social media platform he may uses. It comes off as less creepy than calling his relatives.
Also consider that he may have changed since high school. You may have better luck trying to find new friends.