I don't know the answer to your question, but I suggest that you post it in the nontraditional student forum. There are many people there who have gone through similar situations, and I think that you will get much better advice there than from the pre-allo forum, since many of us our kids in are 20s! I wish you luck, though. 🙂 I hope you can find a way to go to med school.
Unless you posted this elsewhere first, I'm assuming some previous posters got lost and didn't realize they were in the non-trad forum? I'll admit that I stopped reading after the first few responses, so I'm not sure how it progressed from here.
Anyway, there are definitely ways to do this. I went back (no kids or husband then) and started from scratch as an undergrad while working full-time. You might have to forgo sleep for a few years if you can't get appropriate aid. If your wife works, that will help. My sister is working on her master's while her husband works on his PhD with two young children at home. They're broke, but they're surviving in Manhattan right now.
I imagine it might be different for parents of older kids. They may have to take out loans for college instead of depending on a college fund. Then again, your tough financial situation may mean they get better loans, grants, and scholarships than they could have gotten without you in med school.
My advice? Hire an accountant or attorney who knows how to assess these things. Keep looking for responses here, because there are some extremely resourceful people (and financial experts) with fantastic advice, but don't wait for it, either. Consult someone who really knows what to tell you.
I'd imagine you are eligible for loans and aid that you can't even imagine exist. As a non-traditional student, I've been awarded scholarships I never applied for, and aid I never heard existed. Once you actually do get into med school, they'll do whatever they can to keep you there, and from what I've heard, this is even truer in private schools.
You're not old, and what you're doing is admirable. It's not going to be an easy road, and you'll have to strike an incredibly difficult balance, but it can be done. Take it from a 30-year-old (non-trad pre-med) who never reaped the *financial* benefits of my mother finally finishing school as I graduated high school, but is unbelievably proud of her accomplishments. Whatever you need to do to be happy and feel productive, your family will fare well as long as you are setting a good example and taking care of them.