You seem to be angry because
- you were not allowed to go to piano competitions
- you hate your old piano
- you don't like the pieces you are supposed to learn
- you are in a serious power combat with you parents, and you vent your frustration through piano playing, which seems to have becoma a metaphore for some other, underlying issues here.
SOLUTION:
- don't blame those absent competitions. I, for instance, have never been to anyone. I don't know what's the point with them, really.
- get yourself a digital piano of solid quality. They are always well-tuned.
- play what YOU want to play. You are not supposed to "hate" practicing and playing, you are supposed to enjoy it. If you don't like - either you find ways to like it, or you quit. It's your life.
- sort out your relation with you parents. If they want a concert pianist in their family, they should become concert pianists themselves. Talk to them, in a mature, self-controlled, calm way, about your dreams, your feelings, your point of view. The one who loses his/her temper first, is the loser.
Forcing someone to practice when they don't want to practice is a major waste of time and energy, and it will kill your motivation in a most effective way. Been there, done that. Maybe you are not meant to play the piano, maybe you have some other interest that is waiting for you, and maybe that's why you don't like playing the piano? Follow your heart. You may very well change your mind about piano playing later on in life, or you may not. What matters is that you do what YOU like to do.