I'm super concerned for your well being and I don't even know you. What screams to me is that the last thing you should do is to try to do anything like start a business. It does not matter if you follow the best advice, and even do everything that you had done wrong right going forward. When you say things like "I hate what my life has become," then just stop what you're doing for a while.

Really. . . just stop.

Now, I know this will be hard to do. You've probably defined yourself as something different than your peers, and your peers (although not doing start-ups/tech etc) probably admire you. Hell, even your girlfriend lying in bed alone is probably saying that you're a mad genius and that's why your on your computer. Anyways, still even with the social pressure to go on, I suggest you just stop.

Spend the rest of the year focusing of feeling better not doing better. Grab some books, take that trip, and just give yourself a break. I'm not one to suggest self-help books but Stephen Covey has this excellent metaphor in 7 Habits about keeping the saw sharp. The saw is you. Right now it seems like the blade is pretty dull from excessive work. So stop and reread what you posted hear and see how you have described what you have lost.

Grab beers with your friends. Spend time with your gf. Save that 5K because 5k is far better than 0k. And on a side note, any person who e-mails you saying that they want to work with you, given how you have expressed your current state, should stop too.