I make decisions at my job daily and stand by it. In my head it's right and I have my reasons.

However when people disagree and confront me I get excitable lose my cool forget what I should say or how I would or should react and quickly stand down.

Immediately after I feel like an idiot recall what I was thinking and my reasons but the moment to stand up for myself has passed.

My question is when put on the spot and publicly questioned how do I not get excitable lose my cool and flounder at my response?