Good one, but not right.
What really happened was this. OP had arranged a special secret outing for a family member , including MiL, to celebrate a significant event. Deadly secret . MiL let the cat out of the bag , hence the OPs fury. Event went ahead but the surprise element was lost.
Fast forward to when the need for revenge has festered in OPs heaving bosom like a volcano. OP and Mil are at an upmarket soft play when MiL spots a favourite celeb that she has had a secret crush on for years. “I’m going to go and say how much I love XX and how much I have enjoyed following their career,” announces Mil, “ Do I look OK.”
OP smiles sweetly and nods, ignoring the lettuce stuck in Mil’s front teeth. MiL gets up to go to the favourite celebs table where they are sitting minding their own business quietly having a cup of coffee.
To OP’s joy she notices that as well as the lettuce teeth MiLs skirt has caught up in her knickers. MiL goes across, gushes over celeb who is polite but clearly not thrilled.
MiL turns to return to her own table still smiling her lettuce smile, and OP sees the celeb not only clock the skirt /knicker situation, but grab their phone and take a sneaky picture of the MiLs predicament. “Oh, XX is lovely,” says MiL, “ I really feel we made a connection.”