Some very wonderful comments have been made here, and I would like to add by saying,
Yes, life is so very worth it!! And you being around is really making the whole world a better place, even if others are causing you to feel self doubt and have started the wheels to turning to make you feel that you don't count for anything.
You have so much to give to this world and don't even realize it. Give yourself a break, your only human and your not alone either, you have many sisters here in your corner. Ok, lets see, lets start by making a list of all the things that make you that special girl that you really are.
your very beautiful, really pretty.
your young, you have your whole life ahead of you.
your very tender hearted and sincere about what you feel and care of others feelings too.
your very smart, and you already know what you want from life and have goals, many people don't even know what they really want until its to late.
all things point to, that your a classy lady.
Start making plans now for what you want to do and where you want to be 5, 10 and 20 years from now, write it all down and make your plans, look at them everyday, short and long term plans. Educate yourself so you can make a good income, because let me tell you girl , living well is the best revenge and a good education will give you the tools you need to survive and make your plans come to be.
Involve yourself in charity's and become a volunteer, you will be amazed how rewarding it is to be able to help others.
Remember that you are just a valuable as anyone, and that this situation with your parents is only temporary. Respect them and be kind to them, tell them how much you love them too, help them when they need it, but also remind them that you where born this way, there are many like you, and since you respect them, could they give your feelings the same respect, is that to much to ask.
I hope this helps, cheer up, your really awesome !!
Suzy