Back in the last century when I was getting married, my MIL wore a white skirt and blouse with a small fitted navy jacket. I didn't think too hard about it, I wanted to give her the benefit of the doubt but she also dressed my SIL in mostly white (SIL has Down Syndrome and at the mercy of her DM).
I was reading this earlier www.msn.com/en-gb/lifestyle/wedding/mother-in-law-slammed-for-disrespectful-wedding-outfit-she-hid-from-bride/ar-BBTeD7Z?ocid=spartanntp and it brought back that memory. But I'm not precious. I wasn't a bridezilla (I think!). But there were other times MIL was just too much! Like the time she "couldn't resist this bargain in your size" bought me a silk nightie and robe in a designer sale. I am very tall but back then I was a size 10. The chosen ensemble was size 18-20.
My DM, who designed and made my wedding dress, told me after the wedding that MIL chided her for not padding out the chest area.
But I have left the best til last. On return from our honeymoon, we were collected from the airport by FIL and stayed at their house (our own car was 50 miles away and it was very late). MIL had the electric blanket on for us in the spare room (it was July!). I switched it off but left it plugged in at the wall. When we woke up the following morning, we found the blanket had been unplugged from the wall, whereby revealing at some point either MIL or FIL had been in our room. 
Thankfully we were fully covered!!
Please tell me your MIL is/was also a challenge??