I'm sorry to hear about the rough morning you had with D16. I can only imagine the anger and sadness she feels right now. I imagine this is all very confusing and frustrating to her, to say the least. I hate that she took her anger out on you in the manner she did. The positive in this is that she felt comfortable letting it all out to you (even if it wasn't in the best way), which means she trusts you and feels safe with you. I hope after her tantrum she felt better. I do understand what you wrote about it ruining your day...I tell my kids all the time that when we have a tough morning, they forget about it within a minute of getting out of the car while it stays with me throughout my day!
With regard to the latest turn of events with your husband.... I suggest you do what is best for YOU and YOUR KIDS in the long run. I know your attorney is expensive, but it may be worth getting some professional advice. I like what another poster said about getting the finances separated ASAP so you don't keep running into the same problems.
While I know the idea of a separation agreement may not sit well with you, it establishes financial and visitation boundaries. I think your husband would benefit from having to respect boundaries. I may be wrong, but it seems he follows a cycle of not coming around for awhile and being distant/withdrawn, to needing something from you (car, money, etc). He starts coming around more and acting nice to you and then asks you for what he wants. When you hesitate or say you need time to consider his request, he gets angry and threatens to file divorce paperwork immediately. He then either bombards you with emails/texts/calls with threats about losing the house, losing the car, taking the kids out of their school or he withdraws from you and the kids until he gets what he wants. Does this sound about right? If so, is this working for YOU, and is it getting you closer to YOUR goals?
The separation agreement would also provide you with a schedule so he isn't in and out as he pleases, stirring the kids and dog up and then leaving. If the two of you could come up with an agreed upon schedule, you could be heading out of the house to GAL (looking all hot, being upbeat and fun and a bit mysterious about where you are going) when he arrives, and then it would be his responsibility to cook, help with homework, straighten up, spend time with the kids, etc. I think then, too, you wouldn't feel some of the resentment that you expressed.
Again, do what works for you and the kids right now. He told you he is still wanting a divorce, right? Then carry on with your life as if you are going to be divorced. Let him have a real taste of what being divorced is like. While you can't MAKE him do the things your daughter wants him to do, you can require him to honor and respect your boundaries.