ExMIL has always been very difficult to deal with. We divorced a few years ago and we've both moved on. During lockdown we have our DD (10) a phone so she could communicate with both of us.
Well I checked her conversation with her grandmother and they're horrific. She takes screenshots of my FB comments on how it shows how much I don't love her. Keeps telling her that I'm a liar and generally just a bad mother. She also says she should stop pretending to look happy when she's with me as she knows she's miserable.
Whenever she gives her a present, she expects my DD to be OTT about thanking her, if she doesn't she starts going on (for days!) About how ungrateful she is and how it's all because of me. My poor DD has to apologise profusely (like she was talking to a judge) and then her grandmother finally forgives her. You can tell she's very distressed (I also found a conversation with her DFs GF where she tells her how upset she is). I find this completely unacceptable but I don't know how to help her.