Sometimes in life we have to pick the best of the available options, none of which may be very satisfying. It takes maturity to see that, and I commend you on your clear-sightedness in seeing that that is where you are at with your mother. Dealing with her will always be difficult and frustrating. There is always the "nuclear option" of terminating contact, but mature adults tend to reserve that for situations that absolutely can't be managed any other way. So you are resigned to continue "managing" as best you can, knowing that it takes an emotional toll on you, but so would ending all contact. I would call that: facing reality. Then, to top it off, instead of being an understanding and supportive ally in all this, your sister adds to the craziness with suggestions of inappropriate involvement in your parents financial situation. I don't envy you the challenge all this is to maintaining your sanity and figuring out how wide to keep the door open to these family members who will constantly be trying to suck you into their emotional chaos. No wonder you've emerged from this family background with the burden of depression. I think depression is often the product of having problems that seem unsolvable. As I started off saying, there seems to be no good and satisfying solution to the question of how to deal with your family of origin. So you recognize that and just do the best you can, knowing that there is always going to be threatening conflict.

Beyond coming to those discouraging conclusions, I think you work at "setting boundaries." This is a non-existent concept in the minds of your mother and sister, so you didn't grow up with that skill role-modeled for you. Plus, they seem pretty talented at demolishing boundaries. You have quite a task on your hands.

With practice, we can improve at anything. By all means, do completely ignore your sister's proposal that you get all up inside of your parents economic situation. Your sister sounds like a great example of what not to do. Sometimes, when people talk, the best response is no response. Always remember you have that option and you'll conserve a lot of energy. Otherwise these people will wear you out in no time. Getting you mentally exhausted is how they render you ineffective at protecting yourself. As I'm sure you know, depression depletes energy, so you don't have any to waste on total foolishness.

Another thing to bear in mind is that what seem like choices on your mother's part may not be. This is, perhaps, the only way she knows how to be. She probably grew up in a home with crazy dynamics, herself.

I hope you get through Thansgiving with some semblance of peace and harmony in your home, but that can be very hard to maintain when you're, basically, being invaded by a hostile force. Your mom has no concept of how to be a "guest." It might be good, if you could rig up actual locks on the doors to the kitchen, so you have a space to work in that you can keep her out of. Hooefully, you can get your husband to be on the same page with you and, maybe, he can help you enforce some house rules. It will be a challenge.