I feel like I'm in mourning

I feel like I'm in mourning, and I feel bad about it. I'm mourning the loss of my little cousin's childhood, she's fifteen and its all over now, its time for her to become an adult and I'm so sad about it. I'm feeling so many conflicting things I don't even know how to describe it. She's had it rough especially these last couple of years. She's had to deal with sexual abuse, her mother and all her craziness, and just instability in her life. But, through it all I've tried to remind her of how beautiful she is, and how she can accomplish anything. I was fighting for her so hard because I saw this coming. The signs were all there low self esteem, crazy home life, lack of parental attention, and all the wrong attention from boys. I saw from when she lost her virginity at 13 to a boy who lied about his age and didn't care about her at all. And now, as if her life hasn't been hard enough its about to get even harder because her life is no longer her own. I spoke to her briefly online today and she told me how in between her mother screaming and cussing her out her mother finally told her that she's HIV positive. She's been positive for the last 10 years of her life, and admits all this stress now she has more to deal with. I'm so mad at her though and I hate that I'm mad at her but I am, because while there have been so many people fighting for her she hasn't been fighting for herself. She's never allowed herself to dream about big things, and I'm mad about that. She's beautiful, intelligent, talented and just a great person but she doesn't see that in herself and it hurts. I just don't know how to proceed because since I've found out this has been the most I've been able to speak on this. I just don't know what to do.