JWS, I'm so sorry that things went south! Did she maybe read or see expectations that you wanted more: "she was so sweet i thought who knows where this night could go"?
It sounds like she was pulling back from being so close to you all weekend, and then it escalated into D talk--is that right?
If you don't do the work for a D, I don't see that she will either, especially with her financial/school situation, so I wouldn't worry too much about that.
I think the important thing to figure out is...what do YOU want to get out of this situation?
I know she is saying outlandish things that she doesn't mean, but every issue that our spouses have has some grain of truth, otherwise we wouldn't be here. If we choose to look at them like this, they're like gifts being given to us, telling us how we need to change to be better people. (I know, I know, gifts that bite hard ;)...)
You mentioned she was really upset because of the way you were on the phone with the mechanic. Have there been anger issues, or other things like that that you could work on for yourself? And I mean for yourself, not for her?
You wrote, "in the book Michelle talks about being nice to service people you interact with so your S can see that you treat everyone well." You did a good thing by calling him back and apologizing--would you have done that even if she wasn't around?
I found this thread a few days ago that I read, advice to newbies from old timers here. Most of the advice in it consists of--make changes in yourself, focus on yourself, improve yourself--these are the only things that MAY bring your spouse back, and the only things that will definitely help you move on and have a happy life and a successful M in the future with someone else if your S doesn't come back. I bookmarked it to read whenever I need inspiration, so I thought I'd post it to you, too:
*180's,GAL, Going Dark, LRT-- not tricks to manipulate your S into doing what you want or to show them what they are missing. They are...to save yourself and stop doing things that attract the problems you are facing now.
Make honest changes-- FOR YOU.
It is in the shelter of each other that people live.--Irish proverb