I am a mental health professional in training. There's a lot that can be said here, but I will keep it to what I think are the few most important ideas I can communicate. If these don't work for you, please comment here and let me know your thoughts.
1. If you intend to kill yourself or someone else, please call this number: 1-800-273-8255. It is a crisis hotline for suicidality. Even if you are highly doubtful that it can help, make the call. Everyone who is suicidal is highly doubtful there's a better way, almost by definition. And yet this number does help the vast majority of those people who do call it. It's worth a chance.
2. You seem to be describing a "major depressive episode." This is not something you should try to address only through self-help or HN (though taking the steps you have taken was an excellent move in that it is going to help you find the next ones to take).
For one thing, there is a physiological element that medication may be required to address. For another thing, the very faculties that you would use to try to help yourself are almost certainly hindered and distorted while in this depressed state. Your problem-solving abilities are likely compromised. Your ability to see alternatives is likely compromised. Your sense of realism in evaluating your situation is likely compromised.
You should seek professional help - from a professional counselor, clinical social worker, clinical or counseling psychologist, or psychiatrist. I would say the same thing even if you were one of those things.
3. There are barriers to seeing a professional for many people. It might be money, it might be stigma, it might be bad experiences in the past, lack of motivation, lack of information, feelings that it won't be helpful -- it's different for different people.
Also, some people will see a therapist one or two times and then decide that therapy didn't work. Therapists are like graphic designers, software engineers, carpenters, or any other profession -- there is variable quality and variable styles. And even among the good ones, some of them may just not a fit for you.
But I assure you there are competent therapists that you will feel a connection with. In fact, most therapists are pretty solid people to sit down with, and they won't have their feelings hurt if they turn out not to be the one to help you -- they'll want to help you find that one.
So consult with a professional. Make a call. Schedule an appointment. Tell them where you are. And if they suck or you don't like them, go try another one.
4. Depression can cause hopelessness, and it feels real and appears real -- that the world is actually that way, that life will always be that way. You can't trust those thoughts and feelings. You've got to take some steps in spite of them. Recognize that it is as if you are under a dark spell. Resist the influence of that dark spell as you try to get it lifted.
5. As I said above, I will check back here tonight to see if you reply to this. Odds are good that you are skeptical about some or all of what I've said here (though if you're not, that's fine too). I can't provide therapy (and this isn't therapy), but I can help with this kind of process of seeking information and exploring your options.
Edit: 6. (Forgot to add...) You should be very very careful with drugs and alcohol right now. Many people who are depressed but not actively suicidal take their lives when under the influence.