Benefits paid to a divorced spouse won't affect the benefit rates for other survivors getting benefits on the worker's record. So even if the divorced spouse is receiving benefits, that would not have any effect on you as the surviving widow.
If you will also receive a pension based on work not covered by Social Security, such as government or foreign work, your benefits as a surviving widow may be effected.
If you receive a pension from a government job in which you did not pay Social Security taxes, some or all of your Social Security spouse's, widow's or widower's benefit may be offset due to receipt of that pension. This offset is referred to as the Government Pension Offset, or GPO.
The GPO will reduce the amount of your Social Security spouse's, widow's or widower's benefits by two-thirds of the amount of your government pension. For example, if you receive a monthly civil service pension of $600, two-thirds of that, or $400, must be used to offset your Social Security spouse's, widow's or widower's benefits. If you are eligible for a $500 spouse's benefit, you will receive $100 per month from Social Security ($500 - $400 = $100).
You can not apply online but you can apply at your nearest SSA office.