Hey,
Just so you know i took the time to read all of this and i even came online to reply to you. I like it when people post a real meaty post i think it gives people the chance to really understand.
Having said that i'm worried that you may think my reply isn't much use. I'm not much good at replying but i'm pretty ok at listening and sometimes thats what you really need, someone to bounce ideas off, someone to care.
To be honest it seems to me that you have a good understanding of your problems and where they stem from. Your post though has a lot of self loathing...it makes me wonder if the way you may speak to others sometimes you are directing at yourself 24/7. That's a heavy weight to carry. Sometimes i do wonder too, if the start of forming meaningful friendships and relationships starts with us. I mean who is going to love us if we don't really love ourselves? I don't think you need to express your feeling to anyone else but i do think you need to sit down and give yourself a break. When you were younger you did what you had to do to get through (we all do that in our own ways) but you don't need to do that anymore. I don't know where you got the idea from that everyone is the same except you...my difficulty is that everyone is sooo different i am completely confused by it all!!
Your post had an overtone of souding lost. It seems that finally all your acting has left you exhausted and going back to your home town has led you to actually sit down and evaluate your life. You said there are ways you could be happy but the price is too high? Why do you think that?
You have not been given one chance - the more time you spend on this site, the more you will realise this...if anything this one post is the start of giving yourself the liberty to have another chance. But noone is going to be able to change you except you. If you feel stuck in a rut then you need to challenge yourself (of course this is difficult when we are stuck in depression so i do sympathise), could you put yourself in different situations - situations where you don't know anyone, an hour or two to try out being the person you are when you are with your 'friend'? Because that person is in there, he just doesn't get the opportunity to come out much.

You do sound like a nice guy actually, but also very angry, lost and hopeless one too.
I hope this post has been able to show that i do care. Look around this forum, everyone on here is totally different from the next person. We all have our problems but we help others when they need support and lean on them when we're feeling too exhausted. I really hope that you stay around and get the chance to meet some of us.

ps - i loved you maths and physics analogys