My parent’s relationship

I’ve been thinking a lot about my parents lately. I live in the UK. They live in France. They’ve been married for 45 years.
My dad is an alcoholic and has had the same pattern for years: In one phase he stops drinking for a few months and then in another phase, he would drink again. He doesn’t want to admit he has a problem with alcohol so every time I see my parents (usually twice a year) I know straight away which phase he is going through. When he drinks, his relationship with my mum is tensed. She hates it when he drinks.

Last Christmas it got so bad she ended up throwing his glass of whisky to his face (even though I was in the same flat with my husband and son) and they had a huge fight. She said it was all my brother’s and my fault because we’ve never done anything. I really thought that was unfair but didn’t say anything.

My question is… Do I clean up my thoughts about their relationship or do I actually set boundaries (eg we won’t stay with you next year if he is in a phase where he drinks/you are shouting at each other etc)?