Needing to make a decision

Azkadellia • Currently just trying to get my body to do what it`s supposed to. Lesbian.
So, I'm 18. Haven't yet finished high school, even though I should have graduated this past May. I have one semester left to complete before I get my diploma. My grandparents are trying to get me to go out to Job Corps to finish high school and get training in a trade of my choice.
They're doing it mostly because they know my step-mother is emotionally/mentally abusive towards me and my dad won't step up and say anything to her. I have, but she always threatens to kick me out or call the cops if I stand up for myself.
So, my question is, have any of you ever been to Job Corps? What was it like, is it a good move to make? Did it help you out any? I'm so confused on what I should do, because I truly want to finish my semester here in town at my school. But, I don't think I can take much more of my step-mother.
Advice, or stories, anything is helpful I just need a second opinion.