I just read that famous hentai "Metamorphoses" by ShindoL last night and MAN IT WAS SCARY. I also felt really bad for the girl at the end (she died), but at the same time, she made so many bad choices. Some were because no one tried help her, and some were because she didn't try to share or explain herself properly.
Don't do drugs.
Edit: an innocent girl blablahblah somehow gets into prostitution and the usual slutfest hentai plot. She slowly falls into depression and misses how she used to be. One of the guys she is with gives her drugs, and while she is high, she experiences her past self and is addicted to drugs as it brings her back to a time before her innocence was lost. As time goes on, her drug habit worsens, and eventually she ends up pregnant. She continues screwing around even while pregnant until some guys beat her and basically kick her in the stomach. As those guys leave, she looks at herself in the dirty bathroom mirror. She puts on her glasses again, and styles her hair back into the girlish braids she used to wear. She decides to inject herself one more time, but this time saying that it's for the sake of her child. The manga flashes to a scene of a mother and her child. The mother says her daughter is the best thing that's ever happened to her. And mommy was in a very dark place before Hana was born and gave her life meaning. The scene flashes back to the present, and all we see are her glasses, blood on the bathroom floor, and a used needle.
The female protagonist, knowing her baby was probably kicked to death in her belly, overdosed and let herself join her dead unborn child in a better place away from the sexual and physical abuse.