I wish I could promise you it will get better. But I'm not a fortune teller. All I can say is that I have known people who've been through similar stuff, and found their way through, and are now more-or-less functional adults with more-or-less decent lives. I don't know what the way through looks like for you; all I know is that there have been other fifteen-year-olds who have been in similarly awful situations, and found a path through to being eighteen, and twenty-five, and fifty and beyond.