Sorry about what your wife is going through. I known many nurses ( CRNA,NP,MSN) who have transitioned to become MD's here in the united states and especially here in Illinois.
First option, she could decide to go through regular path by applying to schools of medicine here in the country. Since, she already have taken a lot of science classes, and have at least a BSN, she can start the process by talking to counselor in many of these schools, to see what are her options.
The second path that many inspiring doctors with careers and families do is to contact school outside the country such as in the caribean. I know quite a few americains who became MD's using this path. You live and work here, but study outside.
Here is one particular school that I can recommand taht is worth of checking is the school of medicine at university of health sciences antigua.
Whatever your wife decide, make certain that the family can endure and afford it.
I hope this help