DFiance booked wedding for September 2020 - we gave out save the dates in early 2019 and then invites in early 2020. Obviously the wedding has been postponed so we sent "change the dates" recently.
Separate background, DF 's Brother is married to an awful woman. Huge back story but lots of emotional and mental abuse from her - Brother has had therapy, keeps a separate phone at work to call people on and basically admits it's shit, but says he wont leave "because of the kids". We have tried to help but that is a whole other story. DF's parents really struggle with this and although she is awful to them (and makes DF's mum cry regularly) they are generally nice to her whilst offering him support where needed because (a) they dont want to make it worse for Brother and (b) they want to see the grandkids. Neither DF nor I have ever really had any major issue with her and generally she has been civil to me (apart from one xenophobic incident). We hate how Brother is treated and how his parents are treated, but we have generally been asked not to cause further issues for them, which we do... we just offer support where we can.
Now to this issue. There's a family whatsapp group that their whole clan send pics of their holidays to. DF barely looks at it and keeps it muted. Just before we sent invites out (long after "save the dates") she had a fit because she said she was excluded from the group. She wasnt - she said she didnt want to join ages before. She then found out DF is an admin - god knows how as it was news to him. She went mad and did a lot of bitching, which we ignored mostly. Generally in person we have been on good terms and we didnt think it was a big deal.
We sent invites shortly after the above issue. We got an email response from Brother saying they couldnt come but good luck. No explanation or anything - they knew the date a LONG time ago so it's clealry not "other plans". We assume it's the bullshit mentioned above but it could be anything else tbh. It doesnt really matter why... fact is, they aren't coming and they didnt give us a reason. DF text, emailed and tried to call but no response. Nothing. DF refused to tell his mum because it would upset her. When we sent the "change the dates" we included them despite this. We still heard absolutely nothing from them. DF still hasnt told his mum.
DF's dad knows (I am annoyed at him because he has spoken to Brother a few times since and didnt even raise it but that's a separate issue). So, my question ---> They keep saying they dont want to upset his mum so will tell her later. It's been months now and the wedding is in 4 months' time (well, it'll be postponed again shortly, but for now it looks like it'll be in 4 months) ans she still doesnt know and thinks Brother is coming to wedding. I think she should know now so she can realise there is a major rift between her kids, and not have it accidentally slipped by someone later or be left to the last minute. His mum is a grown woman who has raised 3 kids and she has no specific MH or other issues which might be affected. I dont think she needs to DO anything, per se, or that she would be able to anyway... but i think she should KNOW.
AIBU and interfering or am I right? FYI - I am not going to tell her myself...