People who are “finding their marriages stressful” don’t walk out and then a few weeks later, deliver divorce papers. People who have decided their marriages are over and they want half of the assets and they want to put their ex-partner on the wrong foot do that. Think how despicable it is to just send those papers with no warning. Right now, you’re in shock and sadness, and who wouldn’t be, but when you start thinking of what he’s really done, you’ll find your anger.
And him walking out weeks ago, and then suddenly dropping these papers on you. That means he has a lawyer and you don’t. Which means you need a lawyer immediately. They can try to protect your assets and your retirement, if possible, and you need one as soon as possible.
My very best advice is to try to separate these two things: 1. let there be an emotional, sad part of you that is heartbroken and mourns your relationship and then 2. let there be a no-nonsense part of you that gets out there and gets a lawyer and protects your assets and realizes your ex-partner has stonewalled you for weeks while planning this and then dumped you in it. You can be both people at once.
Also, please protect and prepare your heart for news that there’s an “other woman” on the scene. Men like the one you’ve described, with sporadic work histories, who are financially reliant on their wives, don’t usually leave until there’s a new woman to be reliant on.