You live in very tough circumstances. It will get better once you get older and can move away. You also will have some therapy sessions which hopefully will begin to be a support to you.
You have many reasons why you won't call the crisis line. You have already deemed that they will not be helpful to you before you have ever tried calling them. It's your choice to pre-emptively deem that they are not helpful. There are online crisis-chats too - that you can find online. If you deceide they won't be helpful to you before you even try, then you are right, they won't be helpful to you.
So then you must find a way through relying on your own resources. This is hard even for adults to do, let alone teenagers with sh*t parents. But you are very bright and very resourceful.
Things can get better. You can make choices to improve the hell you are in. You seem unwilling to make any of those choices and yet you consider an extreme choice as viable - causing your own death.
I have lost people to sucidie. I have struggled with suicidal thoughts myself. When people choose to cause their own death, it leaves behind pain and trauma for others. You may think that no one will care or miss you - that's what my friend thought when he died. Yet myself and many others were very deeply wounded by his act to choose to die.
You did not chose your family or your terrible circumstances or to have PTSD. You have made good choices in the midst of it all. You learn to be more assertive and stand up to bullies. You chose to learn martial arts as a good outlet for some of what you feel. You chose to reach out for help and support here.
You can keep making good choices that will help you endure this horrible time of life you are in and because a very successful adult who gives a lot to the world. Please don't give in to your PTSD symptoms and let the suicidial thoughts overcome you. Focus on the good choices you can keep making, and you will get through this to a much better time.