Should i feel sorry about someone?

so my brothers dad is a "Drug Abuser(crack)" and he came over today. he used to live with us but nobody liked him so my mom kicked him out... his own family doesnt even want to care for him. its been about 2 years since he hasnt lived with us... one day he came over and some drugs fell out of his jacket and my baby niece got a hold of them and some bad things happened...she almost got taken away from her family... but anyways my brothers dad had got a job at walmart and got a place to live and he was doing fine for about a year but he was still doing drugs... recently he just got fired from his job and has no place to live and just found out that he has prostate cancer... i really dont like him but for some reason i feel sad that he has to go through this.. one side of my brain is like: who cares its his fault... and the other side is like: thats messed up