It is just unbelievable that you would be invaded this way, without invitation or consent...the Bagworm shows up periodically in violation of our agreements ( I am trying to get Protection Orders in place of the stipulations to prevent this in future), and it is a violation of the most egregious sort. At least you got some prior warning. Does she expect you to pick her up from the airport or to stay in your home?
If you are going to see her but are having a great deal of trouble, you might absent yourself frequently, and have friends with you who understand the situation when she comes.
When my father was suffering his final illness, I tried to be as fortified as possible when I would go to help him, and took breaks when he became too tough for me to handle. I would walk down the hall, whatever I could do to clear my mind. His wife had virtually abandoned him and I just couldn’t leave him alone to fend for himself where he was. When he passed I was sad that he had been abandoned by the Stepmonster in his infirmity, but I was comforted in that I did not reciprocate the abuse, judgment and coldness that they both heaped upon me, and had done what I could for him. I think that I would be tortured by it still if I had reciprocated unkindeness. Still, I was exhausted by the whole thing, and it took everything that I had to manage to keep my equilibrium and guard myself from their attacks.
Do what you can and no more- don't wait until your nerves become brittle and you start to snap! Do what you can to make things enjoyable for yourself- take a stroll, take a nap, eat what you enjoy, walk your doggies, go to the gym...mom can tag along. If you are doing what another person likes and what you don't, it makes it harder to cope when they complain IME.
Do your duty, both to your mother and yourself. You do not owe her a full disclosure of your life, thoughts and feelings. Find out the status of her health, etc.- you are the adult now. Do not expect her to change- it is not impossible, but highly improbable. Do not grant her access to your vulnerable spots. Be kind but do not expect kindness in return- if she indeed behaves in a loving way, that will only be a bonus.
Hopefully your Aunt will be there for you, and take the edge off...