Conditions at company have been worsening for several years, we are at 1/4 the headcount of a few years ago, but are still contractually obligated to support a wide variety of legacy products that have warranties, so the amount of work has not shrunk like the headcount and revenues have.
As things have gotten worse after rounds of layoffs, I've tried to stick it out and show perseverence for about 3 years now. I'm not quick to give up at the first sign of adversity. I've also been looking around, but the job market is dead in my area.
Things have now deteriorated to the point where nothing I am doing is anything I would put on my resume, and the technology is so old that it is another impairment for me to find a new job. We are having to be very creative to keep old systems running with no budget.
Latest news today is another restructure, to the point where I'll be spending most of my day doing essentially junior tech support. My title is IT manager, I have 24 years experience and have not done this type of entry level work myself in over 15 years. If I had no job, and was offered one with this description, I would not take it.
I feel this is a constructive dismissal, even tho the salary is not reduced, since they are laying off more folks.
The environment is toxic, I have trouble sleeping at night, and have been self-medicating with some drinks to try and manage my stresses. I DREAD going into work each day. This clearly cannot go on.
My wife has been bugging me to quit, even with nothing to go to immediately. We can afford it, no kids, mortgage paid off, she makes good money. I am fortunate there compared to some who are paycheck to paycheck. I can't retire permanently yet, but if I have to take year or more off, we will not go bankrupt. My concern is the appearance of this to future employers.
I know employers tend to suspect that people who quit with nothing to go to are usually really being fired, but given the chance to quit first.
How can I convey that is not what happened without going into a long explanation that will probably sound like a misleading excuse or lie, designed to cover something up?

You can't fudge the resume
MT hadiscussed "tricks" people use to cover gaps in their resumes likes putting only the years they worked, and not the months. They don't work, everyone knows what is going on, and it gives a bad taste to the recruiter reviewing the resume. A gap will generally only hurt you getting in the door for an interview. Accept the gap on your resume, and move on.
Once you're in front of a recruiter or hiring manager, you can explain the situation (constant downsizing, dwindling resources, etc.). Most other people have worked in a suboptimal situation, and will understand. You managed to explain it in a few paragraphs here, you can get thropugh that in a minute or so during an interview (probably shouldn't mention the drinks). Wow the hiring manager by being prepared for the interview, and discuss the components of the work that you're good at.
Everyone has to make decisions for themselves and their family. It sounds like you'll be doing easier work for the same money and title. I'd recommend at least considering staying if you think you could relax a little by knowing that you're still doing good work, but that you are looking for another position. If you can't, and it's still harming your family life, then, there is a risk, but it's manageable, and once you get into the interview, that won't be your biggest concern.
Thanks very much for the
Thanks very much for the input. Having an employment gap somewhere on your resume, given the economic conditions of the past few years, is not the big deal it once was. I was more concerned about the optics of leaving a place voluntarily with no other job lined up. It's not so much having the gap at all, but the reasons for having it, if they press me on the matter.
If it was simply easier work for the same money and title, and I could shed my current duties, sticking it out would not be a problem. All the project and software dev stuff I was already doing, from assuming others people's jobs who were laid off, must still continue. As bad as it is to be doing the work of several people, at least the work was technically challenging enough to be marginally endurable, even tho I was learning nothing new.
Now with the helpdesk departure, I have to do his job as well. I know from years of being his boss that it's a 40-hr a week job. It's also the kind of technically complex environment where putting out IT support fires has to take priority over everything else. If a person's PC cant talk to the network, they are dead in the water, so it must be dealt with immediately. Which means the continuous interruptions will render me less productive than ever during what little time I will have left for work relevant to my seniority.
I know that the helpdesk work will consume most of my week, but I will still be under pressure to show some progress on the other projects as well. Given the ever-increasing hostility of my boss, (due to the increased pressures he is under), I expect limited compassion for my plight.
To be honest I see a lot more
To be honest I see a lot more danger with trying to hang on in a highly toxic environment than I would with having an employment gap. Bad things can happen in these situations, and you could end up thinking, "I wish I'd have gotten out while the getting was good."
Fill the gap with something.
Your story can explain why your job description rapidly went the opposite direction of where you wanted it to go (obviously without any negative comments about the company), then you decided to step aside. Instead of stepping into a (gap), step into education, or contracting work, or anything else you could put on the resume as an explanation that you left the company to do something, rather than left the company to do nothing.
Thanks mrreliable, I was
Thanks mrreliable, I was leaning strongly towards getting out of the toxic environment at all costs myself. I starting poking around online, and I found a large number of people (even authors of career advice blogs, etc) giving contrary advice. Much of it can be distilled into: "unless you are being physically harmed, sexually harassed, or pressured to conduct illegal acts for which you could be charged, never leave a job with nothing to go to as it creates a HUGE red flag in an economy where good jobs are scarce as it is."
I'll admit my personal
I'll admit my personal experience affects my perspective on this issue. In my younger days, in one of the first jobs I held, it was clear the company was circling the drain. I considered bailing out, but decided to stick with it. It was a retail store, there was inventory shrinkage, and I walked in one morning and fingers were pointed at me. Talk about wishing I'd have bailed out earlier instead of being escorted from the premises. I was later cleared after the shrinkage continued and the person who pointed their finger at me was caught with merchandise in the trunk of their car, but it was still a very unpleasant experience.
From your description there is damage being done and it's affecting your personal life. I think it's good advice to try to stick with it from a personal marketing standpoint, but it's not as if the situation is merely annoying.
Make a plan
I'd start looking actively for a new role with every non-working second. If you can afford it, quitting without a backup is fine. But don't quit without a plan. Start to get your network warmed up, polish the resume, think about where you're going, and make sure it's not just a "i quit" at the end of an especially bad day. Go through the "how to resign" podcasts and make a plan that works for you.