Fine ... if they don't pay you direct then they will not issue a 1099-R however your EX also cannot issue a 1099-R. If the divorce decree says it is alimony and it became final before 1/1/2019 then it is considered taxable income. You do not need any "form" to enter the amount you were actually paid. And the ex cannot give you any of the withholding he had on his 1099-R form ... you must figure out a way to pay the taxes needed in another way.
