Worried about mum coping with dad

Hi everyone. I haven't posted here in over three years, but I felt like I needed to today.

A quick update on where I am now in my life: last September I moved overseas to study. I love my course and it has been a way for me to finally get away from all the problems at home with my dad's drinking and focus on myself and my own goals in life. I come home to visit during university holidays, mainly because of how close I am to my mum and I really miss her while I'm away. But lately I've been so worried about how she is coping with the whole situation with my dad. She puts on a brave face, but I know she only stays for the sake of my sisters, and the stress takes its toll on her physically although she would never admit it. I know I have to carry on for my own sake, and my mum wants that too as she's proud of what I'm doing. But I'm so worried about her and I don't know how to cope with that. She's the most important person in my life and the one who has always supported me, and if I was left with just my dad in the state he's always in, I don't know what I would do.

I guess I just needed to get that off my chest.