My MIL wants us to give her a huge loan to keep her dog alive. She's calling us selfish because we have our three y/o son in Montessori and won't put him in at home daycare and give her the money to help her dog

My mother-in-law's one year old dog is very, very ill. She has poured tens of thousands of dollars into her dog and the vet has said that even if she continues aggressive treatment, she doesn't think that the dog will live more than another year at most.

My mother-in-law is now at the point where she is asking us for financial help. She needs just over $11 000 for the current vet bill and needs at least $2 000 every month for meds and care until she can figure out how she can afford things for the dog.

My husband and I cannot afford to help her, but she seems to think that because we send our three year old son to Montessori School, if we used that money instead to help her and put him in cheap at home daycare, it would buy her time.

My husband and I realize that she's very emotional right now and not thinking straight. My husband is an only child, and has explained to his mom that this is an awfully hard situation. Even if we put our son in at home daycare, we're not going to be able to give her the money she needs. We can't afford it.

As it is, the prognosis with or without treatment is the same for her dog. The poor thing has cancer (and several other expensive health issues) and will die. My husband explained that our son was on a two year waitlist for Montessori and even if we did take him out of Montessori, we still can't afford to give her the money to keep going. She has called us heartless for refusing to give her money.

We live on a very tight budget and have made lots of financial sacrifices to have our son in Montessori. While we might be able to give her a couple thousand dollars now, we certainly can't give her $11 000, and certainly not at least $2000 each month. We explained to her that we can't afford to lose that money. Also, she doesn't know when (or if) she'd ever be able to repay us and that's too much money to lose for us.

She's calling us selfish and saying that our son won't even know the difference between Montessori and at home daycare, which may be true, but even if we did do the switch, daycare spots are hard to find here and he thrives at Montessori. If we can't find daycare, then I will have to stop working and stay home so it's not as simple as just changing daycares. Right now, we have excellent reliable daycare which is why I can work.

How do we kindly and delicately talk to her about this? This dog means the world to her but the situation is not making her think straight. In the end, we can't afford to help her. She has done so much for this dog, taking it to literally anyone and trying everything. The dog is beyond saving and while all animals deserve to live, this poor dog is going to die no matter what is done.