My sister triggers my flight response often, how do I regulate myself in the moment?

How do you guys regulate your emotions in the moment?

My sister A has bipolar and is up and down constantly. Her ups are angry. Her downs are angry. Everything is loud. A conversation is not possible. Every day im on eggshells, unaure if shes going to be nice, angry, or suoer angry :( I want to focus on myself and my own reactions. Thank you guys in advance :(