Helping estranged parent in their old age

I'm estranged (recently) from my mom. My sister and I had a conversation about helping her out with bills or a place to live, when needed. I said I couldn't afford it, even though if I sold my vacation home, I could. But, it's our dream to have this vacation home and I saw Mom spend money to achieve her dreams. Plus, She is awful to me, spewing vitriol if i don't do what she says. So, I have no contact and have blocked her.

However, I dont' want my two siblings to have to bear the burden themselves. This is difficult.