Selfish son hates me helping his ex

SAYS I'M NOT ON HIS SIDE

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MY son has always been a selfish, uncaring person.

I blame myself for spoiling him as a child. Now he's an adult and, sadly, hasn't improved with age.

Last May he left his wife and young children to go off with another woman. I begged him not to be so cruel and self-centred, but he walked out all the same.

He's pushing for a quickie divorce and being nasty about it.

I can't help but hate him. I know he's my own flesh and blood but he's a horrible person.

I'm supporting his estranged wife and my grandchildren the best I can. But he doesn't like it.

He's saying I have to take his side and cut my daughter-in-law out of my life and only deal with him regarding the children. Otherwise, there will be "consequences".