to you! I think you are doing great despite all of the craziness that is your life! Please remember that. I have no way of knowing whether MIL's gift was malicious or not but I can relate a very similar story myself.
About 5 years ago, my MIL (who is about a size 18-20 herself) bought me a seriously fugly sweater set for xmas. I kid you not--it was tan with brown accents--not a good color combo for me. But here's the kicker, it was a size 20 or 22! I was no where near that size. I was probably about a size 16-18 at the time. So I returned it to the plus sized store from whence it came. It turns out that she had spent a ridiculous amount of money on it! I did have a hard time finding things in that store because I was between the smallest size at the plus size store and the largest size at their sister regular size store (Christopher Banks & CJ Banks). That and I don't really like their clothing anyway. I guess I do not appreciate appliques and embroidery matchy-matchy sets enough. I ended up getting 3 sweaters and a pair of pants (that never really fit very well) at the plus sized store and a skirt and blouse at the regular sized store. But the staff were not very forthcoming that my store credit could be used at either store either. Well, that's enough of that story.
I do like the idea of jewelry or maybe some fun accessories like a scarf or belt! I would try to approach this gift that your MIL's intent was positive.