For those interested ... this document is what you're looking for if you want proof that:
a) Non-citizen Thai spouse must live in the USA for 5 cumulative years to draw widow's benefits on your social security record.
b) Non citizen Thai spouses with 5 cumulative years livings in the USA can live in Thailand and draw widow's benefits on your social security record without returning to the USA periodically.
Rules are different for widow's of other countries. For example, Japanese widows don't have to live in the USA even for one day to qualify to draw widow's benefits on their deceased spouse's USA social security record.
https://www.ssa.gov/pubs/EN-05-10137.pdf
Your Payments While You are Outside the United States (40 page pdf document)