now the following I parted long ago. and what about my ex-wife. Would the benefits I would receive affect the amount my widow receives?
It won't, the benefits your ex-wife would receive won't affect the benefits the rest of your survivors would receive.
And for my parents, what benefits can they receive?
They can get the survivor benefits if you provide at least half of your parents' support and they are not eligible for retirement benefits higher than the benefit they would get as survivors from your record.