Threats of "filing" / Past crimes

My stbx has drafted a wildly one-sided separation agreement. It contains property, custody, and child support. I’ve countered with a property proposal only, stating that custody and support were way more important to me, and I’d like a little more time to consider all of the variables. He took 3 months to draft this agreement, while I took only a few days to counter with the property agreement.
Now, a week later, I get an email from him saying that he and his attorney feel that they only want to move forward with all three, not just one. And, if I don’t sign the agreement, it’ll seems as though we won’t work this out and he’ll be “forced to file”.

He’s threatening me to “file”. I asked him, “file for what”. He told me, “custody”.
I know him well enough to know that this is a scare tactic to get me to sign that very one-sided agreement. How is this fair?

I asked the other day about the QDRO. And this is specifically why I only wanted to settle property first. Without my entitled share of our assets, I can’t get a home/apartment for the kids and I. How would I possibly win any sort of custody case if I can’t show where the kids and I would live? (which I wouldn’t know until I knew a definitive date that I’d receive my settlement.) Currently, we share the marital home. I’m here all day, every day caring the for the 4 kids (we homeschool), and I sleep over 7 nights, then he’s here for next 7 nights. When I’m not sleeping here, I’m in a one bedroom apt.

How can this be ok? Is there not some “hardship” provision? Wouldn’t it be frowned upon that he’s using the custody of our children to get me to agree to agree to less than my entitled share of our assets?

Lastly, how long is too long to be able to bring up a past crime? No, it was never reported. But, it was told to others at the time it happened. It would be a deal-changer, to say the very least.

Thanks again for your time. It’s much appreciated.

Any person is free to file a lawsuit for the issues of custody, support and property division at anytime. There is no law that gives folks any period of time to work towards an agreement.
If you cannot afford a place, you need to file an action for spousal support and child support in response to his lawsuit, or file suit first making those claims.
Even if you are awarded funds via QDRO, that process takes a while, and those funds are not accessible to you without paying severe taxes and penalties for early withdrawal from a retirement account.

I do not practice criminal law and cannot answer questions regarding the statute of limitations for various crimes