Sad circumstances in the family. Early last year, after a two year battle with depression, DH's father passed away by suicide. They live in a different country and this occurred across covid, and MIL didn't share with her two sons the ins and outs of what was happening with their father so it was a massive shock to them.
Fast forward to this year - June. There's always been tension between MIL and DH's SIL. They've been snipey/grumpy with each other for years. They both critique the other a lot, and it's simmered in the background. With her DH gone, MIL struggled to be as patient with her and snapped at her. The situation involved my daughter (I wasn't there) but apparently SIL made snipey comments to DD (7) when DH & DD visited e.g. should be eating pasta properly with sauce/her dd's did. MIL told SIL to "stop making negative comments about DD". It wasn't well-received, SIL was crying, her DH was cross.
MIL and BIL have chatted since & they have both shared lots of things they are feeling about the other. MIL's sister is ill at the moment so she told BIL she needed space.
Now it's August and I'm visiting with DH and DD. I suggested to DH that I take DD to see her cousins for a coffee/park play date as they are close. I asked if it would be OK and to check with his DM. He said it would be fine (I later find out he didn't check with her directly). We agreed as DD is an only, her relationship with her cousins is really important and she might not see them again until next year. It's nice for the girls and I will be there if SIL says anything snipey (I've only personally experienced her be a bit snipey once when dd was having a mega tantrum.) There was no expectation for DH (who has taken his mother's side and out of loyalty won't come) or DM to come.
I mentioned last night to her that I would be popping by for a coffee with DD to see her cousins. MIL was extremely upset, won't speak to us (only my DH when I'm not there), she went off for a drive to cool off. She says I have betrayed her as she was sticking up for DD (the argument isn't really about that - they have bigger issues & she says she is not ready to listen to her son's feelings about them). She says that none of us know what she's going through, she opened up about more scarring things that happened in the lead up to FIL's death/things he said. My DH came out of the conversation with her fragile and snipey to me but later apologised. I'm getting the silent treatment from MIL.
TBH I've always felt things between MIL and SIL are tense. I'm unsure whether to cancel seeing SIL & cousins. I hate all this arguing, MIL has said she doesn't want any pressure to heal the relationship so are we expected to stop the girls seeing each other until then? I was thinking of maybe popping by for an hour then picking DM some flowers up on the way back.
Perspective greatly appreciated. It's created a tense atmosphere in the house.