I think I would start with don't be afraid it will all be ok. I would want her to know that no matter what you have to endure now, you will make it through and the stronger you will be. This situation now does not define who you are, so never doubt yourself into feeling worthless because you are far from that. You will find love and be loved more then you can believe right now. There are good people out there who will truly want to be around you for just you. You are smarter then you think, you are creative in your own way and one day you will understand this. You have a lot of love inside you right now just waiting to come out. Hold on to that and just know there is a reason for your life, for your struggle for all your pain. You will trust someone. You will be safe. You will have a million reasons to be here on this earth.
At this time in your life you will find all of this hard to believe, you will this hard to even consider a possibility, but down deep trust your own heart, that little feeling that keeps you trying, that makes you smile sometimes. As much as you can block out what's going on around you and know there are better days coming. One day you will meet a man, His name is God, He will lead you to a family that I know you can't imagine now but it will happen. There is a whole big world out there that you dont even know about yet so keep living so you can enjoy it. There is so much good coming your way, you just have to wait a little longer. Keep reading and keep writing your thoughts, its the best way for you to feel better at this time. One day you may write something that others will read and they to may feel comfort. So trust me, love yourself and keep a thought in your head, that in time it WILL all be ok:)
Whoever reads this ask this question of yourself. I was surprised by my answer. Ecc 3:1 as a child I may not have believed this, but I do believe things happen for a reason.