Deep breaths. Can you remove yourself from the situation? I find that when my DD is pushing my buttons, leaving the room even for a few minutes gives us both a chance to centre ourselves. Sometimes that is all it takes, and sometimes the issue still needs to be addressed, but we can do it from a calmer place.
I agree it is an interesting and rewarding age - with lots of room for growth of both parent and child - but it is not always easy.
Yes.....also learning when a response is needed, and when it isn't, has been very helpful. Don't quite have it mastered, but I'm working on it.