Yup. Been there a few times.
Notably three times.
Once just after high school. Seemed I would never learn to cope and never have any friends I didn't have to buy. That was about a 2-year low. At the end of it, I had figured out who I was and what I would or would not tolerate. I found the man I would marry and the first of a handful of good friends.
Once just after college. Said man, listening to his paranoid parents, decided that I was going to cheat on him, I was not going to move with him, and I had stayed with him through 8 years of struggling through engineering school because I was only after his would-be paycheck. That set off about a 4-year low that I spent honestly believing I had to earn his (and his parents') trust and respect by anticipating his whims and kissing his ass.
Just a few years ago-- at the end of the last low, actually-- my dad died, my stepmom's sisters decided to run me off, my relatives basically said, "Nope, too much trouble" and turned their backs on me, my in-laws turned on me again, and the therapist(s) I tried to see for the resultant depression decided that having AS meant I probably deserved to be treated that way. That was about an 18-month low that ended in the suicide ward and 30 days of intensive outpatient therapy, followed by two years of (ongoing) regular therapy.
Now there are good days and bad days. The good days are pretty much regular, the bad days run in strings and deeply suck...
...and they're getting fewer and farther between.
So I'm glad I'm not dead.
Go ahead and feel despair. Roll in it, wallow in it, because right now despair is eating you up and life sucks. Denial is stupid.
But don't give up. Don't quit trying, and don't die.
You might not have seen the bottom yet.
But it has to be down there somewhere.
When you hit it, you can roll around and scream some more. Then you can find your feet and start climbing up.
When you've been laying on the bottom, "In a hole climbing out" feels pretty damn good.
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"Alas, our dried voices when we whisper together are quiet and meaningless, as wind in dry grass, or rats' feet over broken glass in our dry cellar." --TS Eliot, "The Hollow Men"