This happens to me too. For example month ago I read about forced prostitution in Nepal. About that poor girl hanged from the wall, beaten, burned, skinned, tortured for days? Weeks? In darkness. She was described as a red stain. She is dead now. Another nameless, worthless body.
And I was here all that time. I wish I could've done something. Save her. But is it compassion, or I'm just jealous it wasn't me, who fucked her up?

I read much more shits like that over the years. Even if I feel bad for wrong reasons I still mourn.

Believing that "who saves one live seves whole humanity" was helpful. Until I fucked up and lost that one person I've tried to save. Haha I was her monster, now I'm just a monster. Suits me better I guess.

About that girl you mentioned, can you locate her? Maybe you still can do something. Soothe her pain.
Be there for her.
She is not evil. And you seem like a pretty decent guy. Maybe there is still a way.