AITAH for not donating my kidney to my little sister?

Kidney disease runs deep in my mom’s family, my grandpa and uncle both died of kidney failure and one of my remaining uncles along with his daughter are both on dialysis now.

My little sisters kidney failed recently and she’s on dialysis but it’s bad and she needs a kidney transplant as fast as possible, she’s only 20 years old.

I am 32M and I have two young kids, I’ve been one of the lucky ones with no kidney problems so far atleast, she’s asked me to please atleast get a test to see if I’m a match and I did and I am. But I decided not to donate, honestly I’m scared for my kids because one of them if not both might need one in the future and honestly I wanna save it for them, I love my sister to death but I know if I donated and in the future they need it I’d hate myself.

My sister actually hugged me and told me that it’s fine and that she still loves me and the kids and said I’m a good dad and that honestly fucking broke me, she’s just a scared little girl herself and I do not wanna lose her. This is the hardest decision I’ve ever had to make in my life. I feel like a piece of shit every single day now but I know if I do donate I’ll feel even worse and I hate myself for it so much. I’m a fucking disappointment of an older brother.

If something happens to my sister it’ll be my fault and I’m too much of a fucking coward to do anything about it.

Sorry for dumping this here I just wanted to vent to strangers because I’m too ashamed to talk to anyone I actually know because i know everyone would look down at me as a disgusting human which I am.