Jeeze OP.
You are merely an object to your MiL & DH, aren't you?
I am so sorry.
If your MiL mentions your weight, or your clothes again, would you be able to tell her to fuck off with her rudeness & ignorance?
Or has the dynamic gone too far now?
What would your DH do if you told him to fuck off with his hurtful comments?
Oh she has zero boundaries she will have no problem opening my wardrobes.
It doesn't matter what her boundaries are. They are none of your business & not your responsibility.
Your business, & your responsibility, is to own YOUR boundaries.
A swift "get the fuck out of my wardrobe, you nosy interfering old dragon" would have done it.
But I'm getting the feeling that you have been conditioned to accept them acting like the Ugly Sisters to your Cinderella, so wouldn't feel able to do that. Is that because your DH would refuse to back you up, & would side with his mother in bullying you?
Do you need help summoning a fairy godmother& Coach to get you away from these horrible people? Genuinely - if you are unable to change their behaviours (& they have no incentive to change, so won't) - how are you going to get away from them?
You cannot go on living like this my dear 