eazybee
My further advice to you is that you let go of the hatred you feel against your ex-daughter in law,which will sour your relationship with your granddaughter, and stop trying to exert influence over your 'passive' son .
I agree with this post, The Mother was wrong leaving a 3 year old with a man who had s brain condition and anger issues, but your son should have dealt with it, not go running to you.
I also think you are intrusive asking the child about her Mothers boyfriends, lay off and let your son deal with it. You are going the right way for this woman to consider not letting her child visit you.
When the child visits do not ask sbout Mothers boyfriends, ask how Mum is, it's not manipulation, it's basic manners. The child has picked up on your attitude so mend fences quickly.
You may not agree with your dil lifestyle, but it seems the child is ok.