Re: Why should I #2?
Just because the divorce isn't final in the eyes of the state, you shouldn't feel bad for moving on. As long as you waiting until it was honestly over and irrevocable for you, then you can always look at yourself and know that you gave it every shot without sullying the waters.
New relationships are an amazing thing, and your brain going's make it even more so. So enjoy and savor every moment and new discovery.
The only advice I hope you heed is to wait a couple years* (at least) before getting engaged again. You need to be mentally clear of the past, process the last 18 years, and give yourself time to reflect on who you are going to be for version 3.0. That can take longer than you realize.
It certainly doesn't mean not to enjoy this new gal, and see just where this relationship can go. But I recommend making a vow to yourself of "Under no circumstances will I remarry before XYZ date which is N years from my divorce being final" and tell any new gals in your life up front that "hey, I spent a lot of years with my ex-, and I'm not going to mentally unwind them overnight and I'm not sure how I am going to turn out. That why I have mad a vow to myself that I would take this time before doing it again, to work on fixing and bettering myself." It doesn't mean any girl you see during that time needs to feel like you are out to play the field all you can, just that you are being careful to do better next time. If she respects you, it should be a non-issue. (Personally I was with my ex- 16/18 years, and I set a no-remarriage time limit of 5 years. I was up front about it, and it was no problem for the woman who is now my fiance.)
What you want to avoid is the classic "rebound too fast" scenario. It's a cliche among men our age for a reason (saw my own brother do this). By setting a self-imposed hard time limit, you make it not about the gal you are with and gives you room to make mistakes and let things evolve past the first 6-months of NRE (New Relationship Energy) and perhaps save yourself from yourself. As I said, if she's the one, she'll stick with you and all that time will be spent growing together.
We walk the plank with our eyes wide open.