Insulting baby gift from SIL

Momma of 4

Before it's assumed that I'm entitled and ungrateful, a little background....my SIL (husband's sister) and I have always had a polite/cordial but strained relationship. She seems to be competitive with us (she even started up the exact same online business that we did a few years ago, and basically tried to become our competition....we found out from another family member a few months after she started up the business). She has 2 kids, I just had my 4th baby last month, who she hasn't met yet.

Her youngest daughter is about 5 months old, and during a family visit a couple months ago we were talking about baby products. I specifically remember us having a whole conversation about how we both hate the snap up the leg body jammies. We were joking about it being the middle of the night and it's dark in the room and you have to line up those damn little snaps with a squirmy baby, and we both said that we hate them so much that we just donate them or give them away.

Fast forward to last weekend. It was my son's 6th bday but at the last minute she canceled because she didn't want to drive in the rain (the party was indoors and it was barely raining but whatever). She sent her brother with my son's bdsy gift and a gift for the baby I just had a month ago.

What was the gift? 1 snap up the body jammies, which we had just discussed that we both hated. That was the gift. Oh and it's a size newborn and baby is already out of newborn size.

Look I'm all for regifting and "it's the thought that counts" but I feel like she gave something that she specifically knew I'd not use. 5 months ago I got her an Aden Anais blanket 4 piece set with a bunny lovie that matched the bunny in one of the blankets. I'm not expecting a fancy gift in return, but a little book would have been really nice, or quite honestly, just don't give anything, rather than give something she knew I hate (and she herself hates) and knew I wouldn't use. It just feels insulting.

My question is, do I still need to write a thank you note? Normally I'd just take the high road, and ultimately I probably will, but even when I go to write a generic "thank you for the thoughtful gift" I just get pissed and put the note away. Or can I just say nothing?