Survivor benefits and divorce

If your divorced spouse dies, you can receive benefits as a widow/widower if the marriage lasted 10 years or longer and you are age 60 or older (or age 50 if you are disabled.)

Benefits paid to a surviving divorced spouse who is 60 or older (age 50 if disabled) will not affect the benefit rates for other survivors receiving benefits.

See here for details :
http://socialsecurityhop.com/en/pubs/survivors-benefits/02-what-you-need...
http://www.ssa.gov/ww&os2.htm