Not exactly the same thing, I know.
Nearly 20 years ago, I divorced my first husband. There was no abuse or anything, it had just got to point that the children were grown with families of their own, and the marriage, which had lasted 30 years, was over.
Our children remained strictly neutral with this, and I didn't badmouth him at all. He did me, but that was his choice. We haven't spoken since.
12 years ago, out of a clear blue sky, and with no warning, he texted our children, saying he never wanted contact with them or the GCs again.
My daughter was devastated, she'd always been very close to her Dad, and he blocked all calls etc so she didn't know why.
My son lives in America and took a much more laid back view - just ignored him back.
My daughter made the decision that she would send him a birthday card, a Father's Day card and a Christmas card (with a photo of the GC's inside) every year.
For 10 years they were ignored.
2 years ago, she received a birthday card from him, out of the blue, and he texted her.
They are back in contact, although the relationship is flaky, and will never be what it was. He will not explain why he estranged her, and she's very wary and untrusting.
A couple of months ago, she had a 25th wedding anniversary church blessing, and invited him.
He said he would never attend anything if I was invited, so I worked out with her that DH and I would do the evening party, so her dad could do the church.
This suited us, because my DH had been very ill, and a full day was a strain.
Six hours before, my ex texted my daughter and said he was too busy to attend.?. He randomly texts her, and she just replies in a general tone.
So, contact can and does sometimes resume after years, but it may not be the relationship you hope for.
So, if it makes you` feel better, then carry on with the cards, but don't hope for too much.
Best wishes 