AITAH for not feeling bad that my brother has cancer?

Hi. I'm not sure how to start, sorry. I'm 22 (f) and my brother is almost 30. He was diagnosed with skin cancer a few weeks ago and my whole family has been really crazy because of that. My sister and my mother, in particular, have been extremely upset and anxious, trying to please my brother with literally everything, and my brother has started using being sick as an excuse to get things he wants. He's tried to do that to me too, but I've always told him no and that he can do it himself, which has actually gotten me criticized by my sister and mother because I sound very insensitive or something like that.

But I really can't feel bad for him i think. I feel guilty for not feeling bad for him since he is my brother and that is apparently what my family wants me to feel, but I can't do it and i don't know what to do about it. He sexually abused me when I was 14 years old (yes, he was in his 20s) and despite telling my family, nothing bad has ever really happened to him.

Like, nobody accused him of anything, he didn't lose any friends, he also threatened to sue me for damaging his reputation if I said anything publicly. Which was crazy. I was never able to sue him either because my parents didn't help me with it; in fact, I'm pretty sure my mom lied to me, saying she was going to take my phone to the police for an investigation. But I think she only did that to read my chats. The most they did was sit him down in front of me, ask him to apologize, and say to me, "Do you want him to live with us or not?" Like, all of that with him in my face. So yeah, we still live together to this day.

I've been telling myself all these days that this is what he deserves, at least. But I've spoken to my mother and I admit I lost my temper a bit, mainly because she was asking me to be a little more sensitive and kind to him and I told her I didn't feel like doing that with my abuser. But she got really upset and told me that I should have forgiven him already, that we're a family and that it was many years ago, and that he dind't do it again since. That we've gotten along very well these years and that he's done several things for me (which is true).

But i don't know. I really have no one to talk to about this and it's driving me crazy. Is it really so bad that I don't want to be sad for him?? I thought it would be normal, but everyone is so angry with me right now. I always thought I'd have the answer to thing like this by the time I turned 20, but honestly, I'm just getting crazier.

That's why I wanted to ask from an outside perspective, because if I'm really acting wrongly, I'd like to try to change. I want to be a good person some day i think. Thanks in advance and sorry for my bad english, i do not speak english very well.