Gilbert's book came out a year or so ago, I believe, and was popular enough that a lot of public libraries would have it, I suppose. You can also probably get a cheap used copy online. I have very much enjoyed the book. He's got a sharp wit, so that makes it fun as well as insightful. He's really onto something in noting that we get ourselves all tied up one way, but life often goes another. I really think you'd like this and find it helpful too. In fact, I suspect anyone going through the pain of separation/divorce would benefit, but it's even good for people in almost any situation in life. You'll gain some deep insights into how you and others think/act.
Good luck fighting over the tax money. My W and I have agreed to split the refunds 50-50, and so we have avoided a fight on that. In fact, we really don't fight. We just don't have any meaningful contact. The only contact is over matters such as "I paid the tax preparation bill today and we can settle that at the end of the month when my credit card statement comes." She then replies "Thanks for doing that."
Good luck with the L on Wednesday. I haven't crossed that bridge yet, but I will be thinking about you and wishing you well.
I'm not surprised to see her interest in where you were. Still, there's not much you can do with that. You handled it well. I bet she does care if you dated but can't/won't think through her feelings on that one. Mixed up indeed, and not much you can do about it unfortunately.