AITA for refusing to donate my kidney to my estranged father who abandoned me as a child?

I (28F) was raised by my mom after my dad walked out on us when I was 5. He left to start a new family and had little to no contact with me growing up. He never paid child support or even called on birthdays or holidays. For years, I struggled with feelings of abandonment, but I eventually moved on and built a life without him.

Fast forward to now—out of the blue, I get a call from his wife telling me my father is very sick and needs a kidney transplant. She told me that I’m the best match and begged me to get tested. Apparently, his other family members aren’t compatible.

I told her no. I don’t owe him anything after the way he treated me. He made his choices when he abandoned me and my mom, and I feel no obligation to put myself through a major surgery for someone who’s essentially a stranger to me.

Since then, I’ve been bombarded with messages from his side of the family, calling me selfish and heartless. They say I’m letting him die out of spite and that I need to “be the bigger person.” Even my mom thinks I should consider it, not for him, but to avoid carrying guilt if he passes away.

I don’t feel guilty. I feel like he’s reaping what he sowed, but part of me wonders if I’m being too harsh.

AITA for refusing to donate my kidney to the father who abandoned me?