You're a part of a business that's failing. Don't get sucked into the dangerous mentality that what you're doing is something -more- than that - it's not. Startups are just small businesses. If yours is failing, then make a business decision and get out. What you've done up to this point is a Sunk Cost. You can't get it back, so let it go. Your business isn't working and the co-owners can't hack it. So what are you still doing there?