Am I a bad person? 😕

Background story is that my nan used to like her drink, until she met this man 6 years ago who broke her down into some empty shell of a person and she's not the strong, tough woman that I grew up remembering. She cries at every chance and drinks every night either at the pub or home and it's caused many outbursts over time, she's no longer with that man but she is still depressed and lonely.

Anyway out of all her children and grandchildren I am the ONLY ONE that walks 2 and a half miles to her house (I clearly don't drive) at least 2-3 times a week and maybe more, but I hate it because she's either never there and tells me that she'll be home soon to see me but then she'll say she saw this person that she hasn't seen in years so maybe she can see me another time etc and I'm fed up of going to her house and seeing no one or a drunk version of my nan because that version cries as soon as she steps in the door, she has a go at me sometimes and calls me boring because I have to leave as it's late and dark or because she's a chainsmoker and my god.. my eyes burn so bad because of the smoke or even if I refuse to drink also.

She also whines at me to stay over and when I do what happens? She drinks and now tonight she is going out drinking so even when I stay over she doesn't want to know. In all honesty I hate when she drinks, she talks crap about how she holds this family together and really I think 'yeah.. you used to but not anymore' I don't like this side of her but I can't stop it, believe me I tried.. I even told her that I will stop visiting if this doesn't stop and she won't change 😕 am I a bad person for saying all of this or even thinking it? 😕