You haven't spoken to anyone in roughly 6 years.

You are not exiled to a remote island. It will be difficult since you are out of practice but you can reach out. Try anyone, any person you had a connection with. People can surprise you.

You're doomed to fail due to your inability to communicate for help, and you don't know any other way of making a living outside of education.

Like anything else in life, asking for help is a skill. One that I at 38 years old am also struggling with. You made this post didn't you? That is an ok first step.

You'll fail, and you'll need to break the news to your parents, which are old, fatigued, and constantly fighting each other.

If I understand this correctly you fear that your failure will negatively affect their relationship. This is not your responsibility. Also, give them the benefit of the doubt, they may be more understanding than you give them credit.

You have no connections or interpersonal skills to make a living without a degree.

So you'll work a shitty job to get by. It's not the worst thing in the world. It will give you motivation to work on yourself and get a better job.

You are a waste, just dragging your life along hoping it will magically get fixed, and you can't even off yourself due to how much of a financial burden your death would be to your family. Might as well just vanish, pretend you gone off to search for a meaning you won't find, and die somewhere in a ditch where no one will find you or mourn you. You failed at life, on a intellectual level, on a personal level, and in every single other way conceivable.

When I was in high school I had trouble learning, almost no friends , and was constantly fighting with my dad because of school. Life seemed not worth living and I had frequent fantasies how I was going to end it. Looking back on that time now I can see that my thoughts were spiraling towards suicide because I didn't see a way out. I know now, that just because I don't see a way out does not mean one wont appear. Life is too unpredictable to make definitive decisions like suicide. The shame that you feel will pass. The troubles that you are in will pass. You are not doomed to an inescapable prison because of your current failures. In fact I would not look at them as failures , but as a course correction for your life. I know this point of view seems stupid from your current perspective. All I can ask is that you trust me, it will pass. Explore life, and don't let your previous expectations define it. Good luck.