My mom said, "sometimes you need to cut your losses", at first. Later, she added their own layer of stress - would they lose their grandkids if I divorced. Ouch...

They, as well as my SIL/BIL all had differing points for different reasons - this was tough, especially when it changed. Their intention is the part to remember; their intention doesn't make them right~

Set boundaries if you need to. Tell her not to contact him if you want to. Maybe bribe the mailperson...or your dad to pre-edit her!!