I can relate to much what you say. I am almost 25 now and I lives like you for the past 4/5 years. I know its not 12 years. But after I quit school I just did almost nothing. I also drown myself in internet. It like a non stop tranquillizer for me. It keeps me away from my own feelings away from reality. I think its very easy to get stuck in this "lifestyle". I know that if I don't change anything in my life I can make it also a period of 12 years.
And also I know if I don't change I would end up dead our homeless. Still I don't do anything about it. I think it's because depression. What you (and I ) experience as the "outside world" is not the real world. You don't have to experience it like that. What you now see as the outside world is not a realistic view.
You also say you don't want social contact etc. But I think you are so much detached from what real life can be for you that you don't even know what you can experience "out there". Of course you can get a panic attack if you would now go outside living etc. Because you are so in-experienced in it.
I think you must quit all addictions, and all things that you use to run away from reality. Stop internet/tv/video games/junkfood(sugar). Just sit down, be around your parents and don't go to your room before youre actually going to sleep.
Eventually talk to your parents a bit. May be they have a good idea what you can do. Take a easy job. It doesn't have to be full time. I know you don't like the job, I know you can't anjoy it. But you have to realize you can't get instant results with getting this. Slowly you have to do everything to get closer to people, to get real social connections. When you can make it to this point you dont even think about going back to youre old life.
I am actually thinking about going on vacation all by myself. Because I now realize recently I have to break this habit of "non living".
You are 30. You can still do anything you want to do. You can have friends/girlfriend/work. You can marry. But don't wait for it.
I know I don't have real good advice for you, but you must tell yourself that there's much more in life then you now can think of.