Everyone has good days and bad days. I mean, we are all human; we experience these feelings not knowing how to make them pass. Life can suck all the energy out of a person and leave them trying to pick up the pieces that they just can't seem to find.
I've had my fair share of good days and bad days. I've had a rough past, but all it has taught me is to take a step back and breathe. I'm stronger than I have ever been and that's what life teaches us. No matter how rough things can be, you need to realize you're stronger than anything and you can conquer it all. I can always tell when I'm about to start breaking down or a bad day is approaching, since I've had a lot of bad days I've managed to deal.
Take a step back and just breathe. If you're in the middle of something and it goes horribly wrong, go outside, get some air or drink some water. Listen to music that puts you in a good mood and makes you happy. Listening to sad, depressing music will (obviously) put you in a crappier mood. It's better to talk to someone about what you're going through. Bottling up your emotions can just lead to your next breakdown that would be even worse.
It's OK to cry and release everything that's been building up. The best stress reliever is working out. If you're angry and need to release the anger, try kickboxing or volleyball. In no way should you hurt yourself or try to hurt people around you so you can feel better about yourself.
Life is seriously sh-tty sometimes there's no doubt, but I really believe things get better in time. I mean, I had a really crappy time when I was younger, not thinking I was going to make it to 18 years of age. But, here I am, and I'm honestly happier than I ever have been, even though I thought feeling like this would be impossible. I only wish to help you and hope that you conquer everything in your path because I believe and we all believe in you and hope you do too.