Wow. Haven't checked here in awhile; this will be long:
Hi, Melissa.

I read your sitch and my heart hurts; your h is being such a dick right now. Expect this to get worse as your case proceeds.
Perfectly normal when THEY realize that YOU realize that THEY will not be the only one calling the shots here.
Heh….it blows their little minds when we finally stand up for ourselves.

My first h, married for 15 plus years, tried the old song and dance about how "we don't need to involve any L's, we'll just save $$$ and do this ourselves….after all, we're both reasonable adults….this will be amicable, uncontested…"

LoL!!! Right…..That is just code for "time to start hiding assets, income, and quickly cut the best deal for myself…etc…etc.." That is the reason he is trying to push you to move things along, quickly.
Well, I lawyered up immediately and I felt so much better just knowing that I wasn't so helpless after all. I needed that so much because I was so hurt, confused, just spinning! I needed to be tethered to reality.

I am so glad you made a decisive move for yourself to contest his ridiculous offer. And it does kinda matter who files first because that can give the advantage of being the one to set the initial court date, which in turn gives the advantage of the rest of the timeline right up to the finalization. "He who files first files best" is my mantra.

Also, as you now know, it threw your h off balance, which is a very good thing. Exhibit A: those nasty, snarky emails he sends are gold, keep every single communication. You will probably be getting more of those gems. They always show the true colors and also can be invaluable as evidence later on.

Quite a few years ago, a poster here actually told me to just DELETE any emails that upset me! Well, I guess you know how remarkably bad that advice was.
Keep everything! Texts, emails, notes, letters….EVERYTHING!

You need to stop responding to most of them though.This sword cuts both ways and the last thing you need to be doing right now is giving HIM any more ammo to use by responding defensively, emotionally, angrily, etc. Stop trying to explain your decisions. I know how much this hurts, but just don't!

When you do respond, stop defending yourself. Keep your responses very, very short and on point; no editorializing. Leave emotion out of it, no matter how pissy he gets, no matter how much he lies, no matter how much he tries to make you feel guilty, no matter how unreasonable he gets.
I know it hurts when they revise marital history, tell you how "happy, happy, happy" they are. Just laugh to yourself, if you can, about the absurdity of his attitude and let it roll off your back. This is difficult; you can do this.

You are getting great advice. The only thing I would add is that you stop giving him any more financial records, or any other info he requests from you that may help HIS position. Just direct him to have his L contact your L with any questions he may have.
Do not sit down with h to discuss ANYTHING other than kid schedules and such. You're not fooled by his phony, nicey-nice act.

You absolutely need to stop tipping your hand to him. I cannot stress how important this is. Just because he asks you for something, doesn't mean he gets it!

He "wants to be friends…" That is hilarious. He is stunned that you can't trust him? I damn near piss myself when I hear sh!t like that. They really are deluded, aren't they?
My first h had the misfortune of chiding me for not trusting him. I shot back, "Yeah…I can really trust a man who walks out on me…" The look on his face was epic. A truth dart had hit a bullseye.

Also, I see some advice here pertaining to the cost of the L's. Do not cut corners here by trying to do some things yourself; it can come back to bite you. Run it by your L. Now is not the time to be penny-wise and pound-foolish.
And stop worrying about "being nice." You are way past that now and that is a good thing. Trying to "be nice" shows weakness, something he thought he could count on. Minimally polite is good enough.

You're doing great; stay strong. You got this.