I'd like to use golf as an example here, specifically, Tiger Woods. When he makes a bad shot, he gets angry and curses. It's a perfectly normal and expected reaction when something doesn't go right. The key is, he allows himself to release the tension and stress that results from what just happened, processes that, and moves on.
In effect, he has just compartmentalized something that put him on tilt, but now he's completely focused on his next shot. Okay, I'm dating myself a little bit with this reference, but my point is, he was doing this when he was the best player in the world.
To get upset with an undesirable outcome is perfectly alright and it's okay to let that steam out. Some people are extremely verbal when doing it, others, not as much. But the key is the same here - about getting over what made you upset as quickly as possible so that you're ready for your next golf shot, or in poker, the next hand. Many players will get up from the table, walk away and a hand or two off, then they sit back down and resume playing.
We all cope differently of course, and many of the resources that others have posted in here are all tools to be utilized to help you recover faster.
I think the one less constructive way of coping is to keep it bottled up, because over time, it's going to build up and the release will be more extreme, which is even worse. It can, in a poker sense, be even more costly than releasing what made you upset earlier, and more gradually.