Hi DLR, first of all really well done on talking to/opening up to your wife!! That can take a lot of strength and a lot of courage!!! And it is really good that you found how supportive she can be as well.
Now you had that drive, that motivation to find a new job, so it's still under there somewhere, if you can chip away at the feelings you have now (and it sounds like your wife might like to help you with that). Sometimes when you know the positive feelings might not last (with you having to walk into another day on the job) it's worth making the most of that positivity.
So maybe write down your feelings at that time inc. "I do have to get another job!!".........and set yourself some goals/steps in doing that with timescales.
Something like tomorrow I will get two application forms.......because you know if you leave any planning until you're at the bottom of the rollercoaster you're not going to have the inclination to do very much, you'll have almost forgotten that drive, you won't know/care where to begin, so at least if you've got something concrete you're to do it can help a bit. And have your wife help you at that time too.
And as for work, can you take a holiday, to take a bit of a break, and look for another job But the job you look for doesn't even have to be as good as the one you've got even, does it? The main thing is your emotional well-being!! What's best for you, regardless!!
But just keep on talking......to your wife.....to us.......and if you think (??) to your doctor. Your doctor may be able to help you to get in a better place to be able to start the ball rolling/to feel better on your own in time (and with support form others if/when you need it!!).
Alison