TvZ Surprise Mutas

I am having significant difficulty dealing with situations where you get surprised by mutas. I know that the ideal way is to scout actively for spire or other signs of imminent muta attack. Then you can build turrets in time, hopefully.

To give more context, here is a replay:

http://ggtracker.com/matches/6490630

I know the major error is lack of scouting. This lead to me getting so surprised in the first place. Assuming all other things equal, what should I have done after seeing mutas in my mineral line? The problems that make me panic is that while I have a decent amount of marines, I need to split them which leads to not having enough marines at a given point. Also, I lose 2 liberators for nothing because of panic. What should I have done?