I'm about to be medically retired, and was taking care of my dad (another vet) for the last year. He just passed away and his estranged wife is trying to take everything. He did not have an official will, so this will go to probate Court. I don't have a lawyer yet but need assistance.
You need to go ahead and retain a probate lawyer in your region. To my knowledge there aren't any free services available to veterans for the situation you describe. This is a civilian problem so you are allowed and encouraged to do what every American has a right to do...hire your own lawyer.
Veterans are often eligible for free or reduced cost legal assistance related to their honorable military service. What you describe is a civilian marital problem that has nothing to do with VA so you're pretty much on your own. From what very little I know of probate, the wife, whether estranged or not, will have the advantage when any assets are reviewed.