It brings out the worst in us, that's for sure.
At one point I used to look at my son and his behaviour to figure out how "I" was. It was days like this that I learned to look at myself...if I was always angry, frustrated, afraid, sad, regretful, resentful and or just plain tired, it was usually about "me" not taking care of myself and allowing his behaviour to get under my skin.
That's the time to move on or move out, before it makes "us" sick.
Hugs