I'm sorry to hear of one of our comrades being in such trouble, and you suffering as you are.
As for your question, I haven't heard of any minimum time requirement for a spouse to be eligible for benefits, but I've been off active duty for a bit, so you could check the web sites I'll list below.
The U. S. government site also has a portal for benefits for surviving spouse after the term of active service.
I hope something here can help you.
United States Department of Veterans Affairs
This web site is dedicated to the surviving spouses and dependents of military personnel who died while in active military service and to the survivors of veterans who died after active service. We are grateful for the opportunity to provide quality information and assistance to family members suffering the loss of their husbands and wives, sons and daughters, and mothers and fathers.
While most benefits are the same regardless of whether the service member or veteran died on active duty or during civilian life, the "Death in Service" button shown below will take you to additional information specific to death in service issues. You also will find information from other federal agencies and organizations that offer related benefits and services to survivors and dependents. It is our sincere hope that you will find the information here helpful in your time of need.
Just in case this is a resource list for information about spouse benefits: