oh dear, at the risk of sounding creepy because we never really talked, talk to me about this, please. I don't want to come of as hostile or creepy or anything, but I've gone through this (and kind of still am, but yeah)
and just
yeah
talk to me please <3

the girl under me is everything i want to say, but i just want to be the one to say it myself

I understand how you feel. I remember being depressed, and having that feeling of being a burden to my family. It was hard. I kept all my pain inside, I had no one to talk to and I didn't want to talk to anyone since I thought I would be a burden to them. I remember putting on that fake smile of mines saying that "I'm fine". I was a rebellious kid. I got into arguments with my mom and all that other crap.By that point I had lost all faith in myself. I snapped. I cried and cried , repeating over and over in my head "please just let me die, I wanna die. Take my life" . After that I realized something , I realized that if I wasn't ever born , I wouldn't have met these amazing people , I wouldn't have experienced love, I wouldn't have experienced anything . I realize if I would have died at that exact moment , how would the people who love and care about me the most feel ? I realized sadness, depression is an option . I am the cause of my depression . I am the one who made myself feel insecure, depressed, alone. I am the one who let people take me as their stepping stone and used me. I was done . As time pasted I learned more and more not to give a about people who don't give a about me. Everyone experiences pain, depression . Everyone goes through something, whether early in life or later in life. But they move on . They realize only they have the power to control their feelings. Not someone else. Also about you're sister , she's wrong. She's wrong for not listening to your feelings and not being there for you when you need help, and you go girl ! You saved a life. And don't worry if you were adopted or not. All that matters is that you are here. And it's up to you if you wanna keep it in or cry , but I'm just gonna say that crying makes you stronger. Take out all that pain you have bottled up and let it out. Look 10 years from now, this problem wouldnt hurt you anymore, your life has just started. You're young. And Your not worthless, you have hidden talents

pretend to be you're fine when you're not or cry about how worthless you are won't change anything.
and don't keep it to yourself. just find someone to talk, it will help to reduce the burden.
last but not least, try to find a better way to grab their heart. one day, they will realize how much you love them :)

That sounds a lot like how I used to feel.
It may take some time, but you have to realize that you're not worthless. You'll always have flaws but you'll never be worthless; there is a reason you're here.
It might be hard to accept and love yourself, but you have to learn how.
And you need someone to talk to. I never had any, so I have issues from that. Find someone who'll listen to you and hold you when you cry.
I haven't found someone like that yet, but I do know that I'm not worthless.
You'll never be anything if you don't believe you're worth something.
Good luck <3