I miss my DiL

My mil and I became good friends after her son and I divorced and became much closer in fact after her son died many years later myself and my husband became her only source of support until she sadly passed away at 93 last year.

Do make contact with her she sounds lovely.

I agree- get in touch. I know several examples like this where mil and dil havea lovely relationship post split and where ds was an utter rat. I would’t personally say anything to him until it’s all a fait accompli - don’t give him the opportunity to veto what you want to do.

Can you meet your DIL for lunch and tell her how much you miss her cpmpany she sounds such a lovely person,possilby she doesn't know how to carry on your relationship after being let down so badly by your son.
Tell your son what you are doing and how much you miss her he has behaved badly and should know how much you are missing your DIL.

I would think that she may be missing you too. Get in touch!

It's only your son who has let her down. There's no reason for you to cut ties with her. Make contact. I'm sure she'll be glad of your support.