What. The. Fuck. Do. I. Do.
Goddamn it man I don't know. I'm so fucking smart and yet I am missing a very basic fact. How do I live as me.
It probably won't help, but you never really know what it is that people need to hear. Maybe this will release you from the pressure of seeking the answer, and that's what you need. I don't know. It's the only thing I feel like I can offer.
Which is... there is no answer to your question. There is only the decision to keep moving or not. Nobody in this world does anything more than waking up every day and doing the best they can figure out. If that's what you're doing, then you're not missing anything in comparison to anyone else. If anyone has some absolute spiritual answer to the question, it's something they completely made up for themselves that has no objective grounding beyond relation to their own internalized self-concept and worldview. And it's great to have a solid set of those. But they still don't comprise an answer to your question, because they're completely made up by each person for themselves. This is the double-edge of being an especially self-aware person, because we know whatever we come up with is imaginary.
All you need is a why, and you already put forth some answer to that in your last post (regard for loved ones). Life is pain for just about everyone. You're already aware that there are things in your life that matter to you more than the pain. So when you go through the same daily process that everyone else does of choosing to do the next thing or not, just keep it in your mental pocket that you've already had that debate with yourself and made that choice, and there's no point in revisiting it all the time. When that dark part of your mind wants to debate with you, just shake your head at it and go "Yeah, you've told me this before, but we already know this outweighs that, so if you have nothing new to add, then just skip it."
I don't deal with self-hate or addiction issues, but I'm still pretty miserable. Almost nothing in my life is what I want, and I have very little hope of things ever being better. But I get up and do the things every day. Because I know that any internal debate about not doing the things just leads to horrifying flashes of empathy for the damaged futures of people who depend on/care about me. Those thoughts know that's the response they'll get, so they don't bother showing up very often. *shrug*