Mil

[Spied]

Mil knows in trying to be as careful as possible re: Covid and social distancing etc.
Yesterday she asked if my DC could go for the day. I said yes, that would be lovely for them(and I could get on with decorating the kitchen).
Today, I drive around to Mil's with my two excited DC to find she's invited the other grandkids too! So 3 households. No social distancing or being careful whatsoever.
Now MIL knows that I'd not be happy with this as she's previously asked for them all to meet up at her house and I've said that they can't as I'm not comfortable with it ( was only two weeks ago when we had the conversation).
DC are excited and I'm unable to load them back in the car as then I'd be the one spoiling the fun and my DC would resent me for it. DC are pre-teen.
I'm ashamed to say I left them and drove off absolutely fuming.
AIBU-she has done this on purpose as she knows I'd feel I had to leave my DC there?
Duped me?
Or was she hoping I'd actually take my disappointed DC back home and bear the brunt of their disappointment so I looked like the 'bad one'.?(She likes to cause trouble).

I suspect this has more to do with the OP not liking her MIL than it does with Covid.

@BananaPop2020, you've misspelled "MIL being a lying, manipulative cunt" incorrectly.

Really? I don’t think I have, and that is an excessive response to what’s happened.

Presumably MIL remembered you turning down a similar set up recently as you were trying to avoid unecessary mixing of households. Whether she agrees with you or not she should respect that, so yes, it looks like she tried to hoodwink you. Whatever your reason, Covid or no covid, a MIL who wants to build a good relationship with her DIL doesn't do that.

I am glad you have collected them. at 9 and 10 I am sure you could explain to your kids you want them to be healthy enough to go to school and see their actual friends so that is why no sleepovers (Or mkre visits to gran) at the moment.