Sometimes life really isn’t fair at all. You have had more than your share of disappointments, tragedies and challenges. The fact that you still have good days is a testament to your inner strength. But it is no wonder to me that you are getting discouraged.
I do have to wonder if part of the mood change a few years ago might be hormonal. That’s why the place to start is with your medical doctor. It’s possible that at least some of what is going on is medical. Thyroid problems, even a vitamin deficiency, can have an impact on mood. Just get it checked out, ok?
But even if you do have an untreated medical issue, you still have experienced a cascade of difficult events. For that reason, I think a therapist would be helpful at this point. A therapist will help you build on that inner core of strength you already have so you will have healthy ways to cope. Therapy will also help you deal with the losses and sort out what you can, and cannot, expect from your family. Many teens find it extremely helpful to have a therapist who can hear their story without judgment and who can offer encouragement and practical advice.
I don’t think you want to die. I do think you want the pain to go away. As you have already discovered, cutting and developing an eating disorder doesn’t do it. Please believe me: Therapy does help.
If there is a counselor at school, you might talk to him or her about how to approach your mom with the idea of getting some therapy. If there is no counselor, maybe you can take a teacher or another adult into your confidence and ask for help.
When you go to a counselor, take your letter and this response with you. It will help your therapist get a quick overview of your issues.
I wish you well.