I am so sorry you suffered from a stroke and that your family has been so heartless.

I say, don't bother for their sake but if you just need to let them know because you want to--mail a letter to your daughter? If it was me, I would still want to reconcile with my daughter eventually. Though I would write the letter, let it sit and then reread it a few times over the course of a few days in order to get it right. It is such an emotional issue that I think the letter needs a lot of thought and not be pushy at all. Your daughter is under the influence of your ex and young so I think you should bother when it comes to her but not expect things to change for a long time. It might take years but, hopefully, she eventually understands.