Uncaring Mother. Is this an age thing or is it normal?

You say that your mom hasn't been diagnosed with anything yet, but in your profile you say that your mom lives at home with Alzheimer's/dementia, anxiety, depression, hearing loss, incontinence and mobility issues. That's an awful lot for her to be dealing with. Perhaps it's you that needs to be a bit more understanding. People that have any of the dementias tend to be very self focused, so it doesn't surprise me that she wasn't sympathetic about your cat. And if she's hard of hearing, are you sure she even heard you tell her? And even if she heard you, she has probably forgotten what you told her if she has dementia, thus the reason for no follow up with you.
You may want to do some research on dementia to better educate yourself, so you can better understand exactly what your mom is going through. Teepa Snow has some great videos on You Tube as well.
I hope your cat is doing better now and that you can come to grips with all your mom is now dealing with.

I'm so sorry about your kitty and the change in your mom!

My mom was never a sympathetic person, but prior to her dementia diagnosis, I began to notice her only response to my occasional distress (one example: I had to have my horse put down) was complete indifference, changing the subject, or insisting my distress or grief wasn't nearly as bad as hers, etc., etc. In other words, no filter whatever. It was one of many of her personality changes prior to her diagnosis. This went along with forgetting all of our previous conversations, constant repetition, etc. Yes, it hurts to "lose" the parent we once knew. It may possibly be dementia. Have you considered taking her to a neurologist or a doctor who specializes in geriatrics? Some are very good at discerning age-related cognitive decline from actual dementia through simple tests.

Hope your kitty improves and can come home soon! I know that would be a comfort to you! (((hugs)))

Has she treated you like this before? If not she could be having the start of dementia or some other health issue. Is there someone who can check on her or take her to the doctor? That would be my next step.

I am sorry you are going through this with your cat. My mom was the same way until after she got a special cat when she was in her 50s