I don't know what state you live in, and can't speak to the divorce laws, but my guess is that this is a letter from an attorney with settlement demands. It isn't a legal proceeding. A settlement offer is just that: an offer. Your H can ask for whatever and probably will. Attorneys turn this in to an adversarial affair and get the parties angry with each other. They will use intimidating language and say hurtful things.
This is where the 24/48 hour rule comes in handy. I use 48.
It means that, upon receiving upsetting news, do NOT react for 48 hours. Then use a little CBT therapy on yourself. It's a piece of paper with 'I want' written on it. Nothing more. The court decides who gets what, not your blustery H.

You have to decide if you think your H is in MLC. You're on the board so I assume so. Please read ALL the resources and advice from successful DBers. MLCers do NOT respond the way 'normies' do. You need to be deliberate in your actions and very rational. Our minds do not want to be rational at times like this, so it'll take work. And practice.
I do not talk divorce with my wife. When I contact her, it's about anything BUT divorce. I've gotten two settlement offers in almost two years. But nothing legal but filing has happened. No disclosures or anything. Financial disclosures are required before anything else can happen.
In the meantime, this won't be settled today, tomorrow or next week. Don't panic. Courts and lawyers like the holidays off too, so chances are nothing is going to happen until after the first of the year. My attorney says lawyers are master procrastinators. My advice would be to seek legal counsel (try a Christian lawyer who cares about YOU and your marriage) and see what your options are and protect yourself. The opposition will do what's best for THEM and not you.
And yes, MLCers do ugly things because the real person has been abducted by aliens and this 'thing' has been left in his place. Believe NONE of what they say and half of what they do. They are deceitful liars. They eventually come out of this, but it'll be a while, and it depends a lot on what YOU do. But you can't let your emotions get in the way.

Blessings,

David

The fires of true love can never be quenched, because the source of its flame is God Himself!
- Shulamith