Inny, I'm so sorry you have such a difficult time with your mother. My husband's mother is the same. The best thing is to totally not respond to any negative comment she makes. Keep on talking as if she hasn't said anything.

Or, if all else fails . . .
Can you pretend to have hearing loss when she says these things? Like, when she says that you are FAT, can you say, "Oh, mother, my CAT is just fine. I have someone watching him at home. My sister doesn't even own a Cat, really?"
If she repeats, just say, "Oh, mother, my tires on my car are not FLAT. Can we move on to another subject?"

Tell her that you think dress slacks are more ladylike than skirts. What if some peeping Tom is sitting under the pew? Who would be in the better position, someone wearing a skirt or someone wearing slacks? Then say, mother you can be so irrational at times.

About the empty toilet paper roll? Weren't you saving those because your abovementioned CAT likes to play with them? And to the "here we clean up after ourselves." A good, "Well, THERE we don't clean up after ourselves, so please allow me some time to adjust."

Inny, don't actually try these suggestions, I was just trying to cheer you up! Hold on! You can make it! I know you can