Lucyloo12
This is so hard for you
I think there are 3 areas to consider:
1. Yourself and your mental health. Dealing with this will help you in dealing with the situation. As advised, please consider seeing your GP about depression. Consider, maybe through your GP, getting counselling. In order to deal with these difficulties you need to deal with the situation in which you find yourself, your own feelings, fears, sadness and depression.
2. Your relationship with your daughter. You are scared of losing contact with your grandchildren and that means that you feel unable to respond , set boundaries, consider how to deal with the difficulties in the relationship I think. That fear is understandably taking over. When she talks about you to someone else and you feel it is untrue, there is little point defending yourself, you dont have to. I would suggest responses like "I accept that is your perspective on me". "I accept you feel like that". That way, you are acknowledging she feels like that, not agreeing with it. The same if she says something about your ex. I understand this is hard, the instinct to defend oneself is normal, but if you know it will result in ciu off and you dont want that to happen, this might be a way to show her that you know your viewpoints are different, without entering into arguments. It also tells her you have heard what shes saying! When she says the kids need stuff just say "Oh!". Then you can decide later what you wish to buy, not buy. If she asks you for money to buy stuff, say you will think about what you can afford.
3. Not being cut off from your grandchildren:
I am sure that you will be avoiding putting the children in the middle of this. Nothing that you have said, suggests otherwise. If you want to continue the childcare do that. If your daughter threatens you with no contact presumably it links to the type of conversations I referred to in 2. above? Perhaps those type of responses would help to avoid this threat?
I think that No. 1 has to be the most crucial for you, in order to deal with this awful situation for you long term.
Please let us know how things go. 