I shouldn't let it bother me so much

I have a person in my life that I really shouldn’t give the time of day. But the thing is, I feel sorry for them. This person has very little friends and has no one to tell their problems to. I am their number one confidante. But I really am starting to hate them. I’m sick of being belittled and told I’m not smart enough. I’m sick of being told the things I do are wrong and I’m not educated. I’m sick of resenting this person because their problems are ridiculous. They never do anything to correct their problems and never take my advice. They are 100% narcissistic. I can’t get rid of them or just ignore them. This person is someone who will be in my life forever. I’m being very vague here and I have to be. I just really wish they could be a normal person but they never will be.