Ok, we have seen a lot of threads by depression/mental illness fighters. But how about the one who will support them? If our loved ones are having depression or any other mental illness, what should I do?

I am saying this cuz I am a bit loss at the moment to support a very close person to me who suffered bipolar disorder illness. I found myself to be not only frustrated, but also stressed out myself to cope with their extreme behaviors. I do understand that the behaviors and they dont really meant whatever nonsense they said due to the illness, but still I cant brush off this frustrated feelings of trying to win arguments, angry etc.

Been reading online and found below book. Currently reading it, and hopefully it can show me guidance.

I am not sick book pdf link

Any tips especially from your own experience will be much appreciated.