You can learn about Dr. Mark Horowitz here: https://markhorowitz.org. His YouTube presentations are tremendously helpful and informative, as his experience is that of both patient and physician. I am grateful for his book, which I gifted to my doctor and to my pharmacist, both of whom expressed their appreciation.
As to my crash . . . I have weaned myself off Effexor twice. I was fine for a period of two months or so, then it was as if a switch flipped: I was terrified of everything, panicky, crying, extremely anxious about every little thing, did not want to leave the house, did not want to do anything, really. (Fortunately, I was retired.) Lost my appetite and twenty pounds, gagged on food, could not sleep, had nightmares if I did sleep, did not want to face the morning--would not have gotten out of bed if it weren't for my dog.
The first time was in 2019. My mother had died and we thought my husband was ill, so I called my doctor and said I needed to go back on "that pill" immediately--75mg Effexor XR (though I had been prescribed the drug for hot flashes). The second time was one year ago. It occurred to me that I'd been through this upheaval before--but this time, no one had died and my husband was not ill. That's when it dawned on me that I was dependent on Effexor and the hell I was experiencing was withdrawal. My online research confirmed it. I tried to stick it out, but I couldn't. I resumed Effexor at 37.5mg XR and then switched to 50mg immediate release in two doses, 25mg a.m. and p.m. Having been on this drug since menopause and having failed to quit it twice, I know it will take me a long time--maybe years--to successfully quit.