Hi "Kitty Dragon." I have gone through depression, and I know what that's like. Just remember, it doesn't matter where you start, it's where you end up. Meaning, that you're not very wealthy, you're from a small town with nothing new to see. Think about the future. What is your "dream job"? Aspire to be that. Work hard towards your dream, research and do the work required to achieve that dream. If your dream is truly "unreachable" then I suggest you plan another career path that will guarantee financial security in the future. Go to college, and get the degrees required to fill that career field.
Now, I say all of this because you mentioned that you could "just leave and be with them [meaning your significant other]" (a direct quote from your above statement). I talk about following your dreams/ensuring your future with a job that offers financial security because it's important to be a woman who is independent financially and in her career as well.
As for your family situation, you should have less frequent interactions with your brother, as this seems to be a potentially abusive relationship—If any relationship starts or feels to be abusive, stop right there and cut the relation, or acknowledge the fact that it is abusive.....get help from a professional (doctor, psychologist, therapist) if this is the case.
Please, don't think of suicide. Suicide would be throwing away all of your untold potential for a better adult life. We are all given one life to live, use it wisely; but also live life to the fullest.
You matter, your life matters, you can come through these times.
Best regards, Anonymous 14 year old :)