You tell the person they are wrong and proceed to explain all the many ways in which they are wrong, your voice rising all the way from vaguely pissy to shout-barking before you finally end with "and furthermore, get f----d."
You're fired now. You just got fired.
You shriek-- no words, just noise-- then pick up a small filing cabinet and chase the person.
Now you're fired and you're probably going to jail.
You don't utter a word. You just stare straight ahead for a time, looking thoughtful, then nod with Great Wisdom and Understanding, smiling sweetly at the person before calmly climbing atop a nearby desk, undoing your pants, and squatting...
STOP. What the hell is wrong with you?
You're going to have to eat some poop in this gig-- that's just the way it is when your job is to create. Sometimes, the criticism will be arbitrary, and that's fine-- not everyone's going to dig everything you do every time you do things. Sometimes, the criticism will be legitimate, and that's fine, too-- not one of us is a perfect product, and we won't always make a perfect product, either.
You're going to want to know what specifically about your creative choices fell flat, and anyone worth their seniority perks should take the time to tell you. Do make sure you know where you stumbled before you have another go, otherwise, you'll be working blind and will find yourself going through this all over again, and that benefits no one.
You're going to need to remind yourself from time to time, this is what a lot of creative work-- any creative work-- is. Sometimes, you're making your own cool things and you can do whatever you want-- you'll succeed or fail based on the strength of your vision and your ability to make it a reality. But other times-- a lot of the time, if not most of the time-- you're making someone else's cool things, and that entails interpreting someone else's vision and doing the best you can to make that a reality, which can be harder.
The bottom line is we try, we learn, and we try again.