Life Is Imploding

Location: Wisconsin

8 weeks ago my husband told me he's been unhappy for years and our marriage is over. Only willing to do couples therapy to work on communication/coparenting. He refuses any attempts to save our marriage- he is fully done.

We've always kept separate bank accounts with a joint checking and savings.

I purchased my house in 2008, he moved in circa 2017, married since 2019. House is only in my maiden name.

We have 2 cars, one has around 3.5k left on it, the other is paid in full. Both acquired while married, but are in his name.

He's on my insurance through my employer

I have a 401k I've contributed to since 2016 with over 100k. He started paying me, a bit less than half, of my biweekly contributions starting in 2021 as he never had one if his own, with the intention we would both use this for our retirement.

We sat down and came up with a figure that he felt would be fair for me to 'buy him out' of my 401k. This was a little over 5k. I made a handwritten statement we both signed. I'm paying him back by deducting half of mutual expenses from the total. He's signing off on each one.

We have a 5 year old (level 2 autism) that will be starting kindergarten next year.

I didn't see this coming AT ALL. I'm doing my best to cope (today would have been our 7th wedding anniversary).

We agreed to continue living together for our child's benefit and split costs for the house/utilities/cars as long as mutually beneficial.

We reorganized spaces so he has a separate room all to his own, as do I.

Plan currently is not to go through official divorce so he can stay on my insurance (he's paying me half of the cost through my employer).

What do I need to do to protect myself? Since I didn't see this coming I'm having a hard time trusting he won't change his mind. He told me not even 4 weeks ago that he wants to start dating "in a couple of weeks".

I have been meaning to get our will put together- can I do a will separate from him? I want to make sure things go for my daughter/her needs.