Tapering off venlafaxine after 12 years

My guess is that your last decrease was too much. Have you heard of a hyperbolic taper? Basically what it means is that one can make larger decreases in drug dosages of larger amounts, but the smaller the amount of the drug you are taking, the smaller the decrease needs to be to avoid withdrawal symptoms. That would explain how you were able to succeed at the larger decreases in the past, but are struggling now.
I am attempting to discontinue Effexor at the rate of ten percent each month. I need to feel comfortable at the dose I am currently taking before I will make another change. For a time, my independent pharmacist created a liquid solution of the drug for me, which made reductions easy to do. At this point, I am counting the granules in a capsule and taking a reduced dose. My pharmacist gave me empty capsules, a tiny funnel, and a small plastic tray to make the task of refilling capsules easier. It's tedious, but doable.
I never mixed extended release capsules with immediate release tablets; not sure how that would work. I was able to switch from XR to IR and vice versa, but stuck with one or the other for the required period of time.
I know nothing about diazepam.
The most reliable sources of information I have found is Mark Horowitz, who went through this withdrawal process himself and then published a book about it in 2024: The Maudsley Deprescribing Guidelines. You can likely find sufficient information online and on YouTube, where he discusses the process in detail. Information is more widely accessible now than it was a few years ago. Good luck to you.
P.S. Mornings are my worst times, but exercise helps me immensely.

I would advise keeping your doctor informed on each step. People have had differing experiences withdrawing from the drug, so while suggestions here can be helpful, make sure your provider is in the loop.

I will say that after my own experience with Effexor, which flipped me upside down and amplified my depression to a dangerous level, as well as the difficulties I and others have experienced while getting off of it, that I've come to question whether it should remain on the market. It's the most consistently complained about medication on this forum. And the fact that you're a year into your efforts at stopping it and still unable to get there speaks to how problematic it is in my view.

Additionally, at least in my case, I was never told when it was prescribed that stopping it could be an extended ordeal. A medication intended to help patients should not present these sorts of problems if it fails to provide the needed relief from symptoms. For those who need to come off of it, it's creating more stress in their lives, not less. Sometimes extreme stress. And since depression, anxiety, and other mental challenges are what it's being prescribed to treat, those who need to cease using it are already vulnerable. They shouldn't have this piled onto their other concerns.

I feel like those of us who have dealt with withdrawal need to express ourselves in places where we can be heard. And do so with experience and evidence, not anger and emotion. A challenging thing, but important if we're to have an impact.

I'm no fan of the current "leadership" regarding health and medical treatment in our country. But I genuinely believe that there are enough issues surrounding Effexor that it needs to be carefully reassessed in an evidence-based fashion. Too many people are having too much trouble with it for them to be ignored.

Just my thoughts.