My mother-in-law is trying to guilt my husband and I into having a lavish Christmas. What do we do?

My husband and I for the last few years have had very expensive Christmases for ourselves and the family. For the last several years, my mother-in-law has been broke and living off of food stamps, government istance, and us. Last year she didn't even bother to give me a gift and she went to the local food pantry and picked out some trial size toiletries for my husband including a PINK puff sponge. Did I mention some of the toiletries had been opened and SAMPLED by her? Basically, the stuff she didn't want she gave to my husband. She spent all of her money (which wasn't a lot) on my husband's sister to buy her a $50 hair dryer. My husband was hurt greatly, not by the lack of cost on his gift, but because there was no thought put into it what-so-ever. Well, this year, things are different. My husband and I have fallen on hard times. I just lost my job a little over a week ago, and my Christmas Eve paycheck was supposed to cover the cost of Christmas. Now my paycheck goes to our car payment as I will only be receiving half of my usual check. My mother-in-law however just inherited over $100,000 from her father's death. My mother-in-law is riding us hard on Christmas and HER expectations of it. She is downright pissed that my husband isn't going to be buying his sister a present. My husband doesn't think it's necessary right now because we have to focus on paying bills. His mom is already lavishing several very expensive gifts at his sister, one of them being a weekend get-a-way for her and her boyfriend. She also wants us to buy gifts for his grandma, but due to a previous heated political discussion she has chosen to ignore her grandson on gift-giving all together this year. My mother-in-law is also expecting us to buy her gifts this year, too and even went as far as giving us a list. My husband just got off of the phone with her and she told him that she would go out and buy presents for his sister and grandma and tell them they were from us but then toss the hefty bill at us if we "weren't going to come to our senses." I'm sorry, but this woman just inherited over $100,000 (she's been bragging to us about it) and I think she is way out of line, especially after the shitty Christmas she provided my husband and I last year. I do not want us to be stuck with a huge bill on gifts that we would have never bought to begin with. What should I do? I am so frustrated, I don't even want to go to my husband's family's Christmas because I already know it's going to end up in yet another heated argument. What should I tell my mother-in-law and how can I make her understand that as much as we want to celebrate Christmas and have done so for the past several years that this year it is too much of an unreasonable request and we'll I-O-U people when our tax refunds come around. Any advice is appreciated. Thanks.