I also want to share my experience with my currently estranged mother in law. The details may be relatable for many on both sides of the issue.
--She is a mother of sons who has struggled with any woman her sons have ever been involved with (this is usually an early red flag). I married her "golden child", which means I never had a chance in her eyes unless I let her steamroll our lives. She ignores the fact that her son's have either physically distanced from her by hundreds of miles or they have distanced emotionally. Instead, I caused her rift because I have a "dysfunctional" family background and projected this onto my husband. She would even use her so-called generosity as a means to control. Yet, my "dysfunctional" family remains close to us and our beautiful children. These same children my mother in law doesn't even know because she chose to make me her enemy rather than her daughter. She forced her own son to choose between a happy nuclear family or keeping his mum as the matriarchal queen she fashioned herself.
--She blames me for influencing her son distancing himself.
This is partly true. They had an enmeshed relationship that she enjoyed more than he did. Healthy boundaries apparently didn't exist before we met and eventually married. It was hard for her to accept that the husband/wife bond was more important to him than her mother/son bond, and that they didn't actually share everything like she'd hoped. My MIL struggled with the concept that not every aspect of his life was open to her. Us making decisions as man/wife as opposed to him confiding in her or asking for her advice made me her villain. I was manipulating him. I was coercively controlling her baby boy. We explained to her that healthy marriages do not involve one's parents being privy to everything. My miscarriage was her wound because she didn't get to know about the pregnancy at the same time as my mum, as if I didn't have the right to share what was going on with my body with my second most trusted person. When we lost our little boy, she never apologized for making it all about her. I was told that it happens everyday, that she had a right to know, that we were evil for keeping secrets from her. To this day she is as unapologetic as the posts I read from you.
I can go on and on about how she tried to turn everyone against us. In the end, the sad thing is that she is a mother with grandchildren and family that would rather keep away from her than have her emotionally manipulating them. My husband is the only one fully no-contact, but the other does not so much a travel back for Christmas. They speak occasionally, but have never been close. A decade on, and my MIL is probably still dripping poison about us in the ears of anyone who will listen. The truth is that after all this time, we are happily married and she is the one missing out. We would have wanted nothing more than our children to have another set of loving grans. They are not deprived of anything at all, as my side has 2 grans, 3 amazing step grans, aunties, uncles, and cousins. It is just unfortunate that my husband couldn't have a mother who put what's best for him above her own wants.
Please do end up like my mother in law. There is still time for your family to heal. Accept where your son and his wife are right now. Think about more than just your wants here. There is hope if you want there to be. But please stop trying to make your DIL a villain. You cannot know the damage this will eventually do.