Hi, clf,
Yes, you have come to the right place.

Welcome!
Your work environment is toxic and getting worse. I think you need a change and it is up to you to make it. I think you need to get out. Coach is spot-on with his advice. The first and most difficult step is to generate the resolve to make the break, and it looks like you are there already. Your kids are in good shape and they aren't costing you anything. It is so wonderful that you have no debts!.
However, it looks like Bruce and I have a slightly different take on your situation from Nords. Judging from what you have said about the company, I think you should be careful about telegraphing any thoughts of leaving to them. It might be perfectly in character for someone to up and fire you. It sure looks like they have taken care to create the option.
In my opinion, you need to find out what benefits for which you qualify ASAP and quietly. Go through the literature you have on your company benefits. Be careful about asking questions of the personnel dept unless you know you can trust them. Read first. Check dates. You should be aware how many days or months you are away from qualifying for one thing or another. You may decide to bail anyway, but you should know where you stand. With 30 years, do you have any retirement benefits yet?
Take the family leave. They already gave you that opening (but I bet they want it to be short). When they try to make you come back, take vacation. Make your plans during your leave without delay. They may be setting a trap for you when you return to work. DO NOT LET THEM BULLY YOU! Know your rigthts and have your plans made. It is a project, and you can do projects.
Do the homework and discuss with your husband. You qualify for COBRA on your health insurance. That gives you 18 months. You may also qualify under state law to convert it to an individual policy with the same company. Check on that. Call your health ins company. Find out where to buy individual policies in your state. Call an independent insurance agent or talk to your present agent.
It is good that you are at least visualizing the possibility of downsizing the possessions and house.
You already know that you can find work if you have to, after the dust settles. You have valuable skills. Consider contracting. You must know some agencies already from your work. Contractors get paid for every hour worked and have emotional isolation from the pressures that are killing you. (If your work is valuable to your company, they may even hire you back as a contractor, if it suits you, or leave and never look back. They wouldn't work you so hard if they had to pay you for it. Our patron saint, John P. Greaney, is quite hostile to the slavery of unpaid overtime. NEVER let THEM set the rate though. I am doing the same kind of work now as a contractor as when I was an employee, but I am enjoying it so much more.)
I do so enjoy a slave rebellion!
Best of luck.
Be well.
Ed