Firstly, you should talk to your parents, let them know that you feel unvalued and that their behaviour upsets you. If they are any sort of parents they should listen to you, respect you and try to change. Of course, the above scenario only works in an ideal world, which our world rarely is. If your parents refuse to change and continue to behave the way they do, then first of all, you need to realise that all the things they say are NOT true and try to keep it from bringing your confidence down. Think of it that they can call you what they want but you KNOW that you are not any of the things they are accusing you of.
Is there anyone else that you can live with? A grandparent/auntie/friend for example? If there is, I strongly suggest that you move in with them at least temporarily so that you can work on getting your self-esteem back and ,aybe even shock your parents into realising their mistakes, as once you're gone, chances are they will miss you.
I know that the situation you are in is terrible as everyone has the right to a family that will love and support them but unfortunately in some cases such as your own this need is just not being met, and plenty of people go through this, hold their head up high, don't allow their parents to take away their confidence and come out of it a stronger person. If possible, however hard, you should try to do the same.
Good luck,
Amelle.
PS: If you ever need to talk to someone further you can private message me or any of the other support leaders and we will try to help.