Yes OP - high time to dump the guilt.
It really wouldn't hurt your DH to understand that pissing off his wife results in worse consequences for him than pissing off his awful mother, either.
You know you can order MiL out of your wardrobe, out of your bedroom, & even right out of your house, don't you?
Especially if you are usually mild-mannered around her, you might find "get out of my bedroom you nosy old trout, I'm done being bullied by you" very effective.
And when she - inevitably - kicks off (& fear of her kicking off is what keep you compliant, right? - so stop fearing it. Bring it on!) - you just repeat, repeat, repeat, one phrase eg "I'm done being bullied by you, get out."
When you have an 'on repeat' phrase, it stops you from losing the plot or succumbing to further argument from the unreasonable person. Because ALL you want to do is shut the argument down.
You don't need to 'win', you don't need her to see the error of her ways - you just need her to get out of your face.
This is your house, your bedroom, your wardrobe, your clothes.
Lose the guilt, & defend them like a lioness.
Because it's not about the dresses, is it? - it's about your boundaries being trampled all over.
Nobody can defend those boundaries but you.
Be as rude & loud as you want. WITHOUT GUILT.
MiL won't like it. Good. Until she adjusts her behaviour around you, that's what she's getting.
There is NO family harmony to be won by you continuing to kowtow to this women, & by default, to your husband.
Teach them both that your rights are as important as anyone else's.
