My ex-wife is suffering from a HLH disease, she asked help from me through our daughter but I refused and I don’t feel bad about it

I don't know where to start, I thought it would work but it didn't. Long story short: she had affairs with 2 men. Now we are divorced, except for raising our daughter. Our daughter is 22 and we have a son who is 25. We were not that intimate during that time, I had neglected her for sometime due to my work and our financial status was not so good either. I caught her due to her negligence for the first time. She had been in an affair for 3 whole years with him, they met with each other quiet frequently, slept in same bed and even shared small gifts with each other. It was more of a "timepass relationship". I believed I had faults, we didn't understand each other and it was just a mistake. We had moved on... The second one was discovered when I was getting anxious about our relationship because there was a point where she wasn't even interested in most things with me and had stopped putting in efforts. person was her work colleague. This was around the time that we had our daughter. I had doubts about his paternity. She got extremely defensive about how I am trying to "remove" our daughter from our life. But I went ahead and did a swab test from a private lab. The results came that she was indeed my daughter. She was 8 at that time, it was a long affair. We had two young children and despite everything, I was coward enough to not leave. She wasn't working for 8 years now. Time flew by, he went to US for higher studies, she was still underage. Then one day, she asked for divorce, just like that, there wasn't any particular reason to it. The matter went till state high court. She got a good amount of alimony and child support for our daughter. According to judges, as I hadn't filed for divorce around that time of affair, they wouldn't consider that. I got the weekend visitation rights. She took her reward for cheating. I did what I could for both of them. I still support them in their choices.

This Friday, my daughter called me, she informed me that, her mother has been diagnosed with HLH, treatment would need about 80Lakh. They knew about it from 2 weeks ago, I got to know that day. She (ex) has funded some part of the treatment but cant do more without selling gold, house and other things and still there would be more bills. She (daughter) was crying that she was going to lose her and wanted my help. I couldn't bear that but there was hate for her in my heart. The anger and sadness over the years and the fact that she has given me nothing but pain had created that deep disgust. With every drop of empathy that was possible for me to spend, I let her know, unfortunately I can't do anything and I do not plan to do more. I am not rich either. If she sells the house, you can come to my house. If you need anything in life you can always ask me. If you want to do something for her, I have no right to stop you, but she is a stranger to me and has nothing to do with me. I will never sacrifice myself even by an atom's weight to extend anything good to her. I know how hard it is to lose your parents, as I have lost them. I can understand her, feel her but I believe I have given enough to her, whether willingly or unwillingly. We talked for about half an hour, she was repeatedly requesting me and describing how she could not bear to loose her but all in vain.

I feel like an evil person, as I held back even when doctors have said that she has at max 3 months of life. After paying the monthly support I earn about 44k pm. I have a piece of land as inheritance which is worth about 50lac at max. She hasn't suffered anything for what she did and this time she should. I know this way of thinking is horrible but I cant help but desperately pray for an intense suffering of her. Some nights I feel guilty, I feel hateful towards my own self and it’s just too much for me to handle....