It is her decision to leave and start over. I think it's important though to keep in mind all the factors that contributed to her decision.
Yes, it was her choice not to sign the loan modifications. But it was your choice not to get a job for 2 years despite her asking you to over and over again. It was your choice not to go to C'ing back then and take control of your depression. Those two years of you not working and dealing with your depression were crucial factors.
You can't change it now but I would advise you to do whatever you can do to get this house of of both of your lives. Foreclosure will be equal consequences - you did not get the job when you should have and she did not sign the papers when she should have. I think 'more time' with this house will send her (and you) over the edge and set you up for a legal divorce that will not be pleasant.
Some women need security and some don't. You knew early on though your W is not skilled at dealing with real life things so her need for security was clear very early on. She may never allow you to provide her with security again but don't prolong the torture.
I'm not being ugly but think about what you are saying? You, as her security provider, could not even handle the house you have now. Why *would* she want to even consider getting a new/better house with you?
You are letting too many of your desires get in the way here.
Stop saying you can't win. This isn't about winning. You had the chance to "win" for two years before she left you and you were unable to embrace the opportunity. All you can do is learn from it and be sure you never are in that place again.
Women in their 30's that can't deal with any sort of real life issue aren't real hot commodities on the dating market. Your W will soon learn that. Or she will wind up w/somebody as needy as she is. One day she will realize the one person who attempted to stabilize life for her was the person she fought the most. She won't see that now but one day she will.