she said "no one wants someone in the midst of a divorce and everyone in the field knows about us." My response that we weren't divorced yet just drew a smirk.

The smirk was probably because your answer wasn't really an answer to what she was really saying, as your answer was your way of "fixing" the alleged problem. Not good validating, my friend.

She's likely really saying that she feels down, she feels powerless about getting a job. She was talking about her feelings. When women do that, they just want someone to listen, not fix.

and be anxious about what she is doing
and I don't know if I could take it seeing her occasionally
And seeing her dating OM would really be hard for me to take.
I probably add to her confusion because with each step she takes towards D, I react
I hope she sees the folly of her proposal
It seems she is determined to maintain her depression.
My W is clinging to her pain like it were some theraputic device to cleanse her of a demon.
Then I just have to convince her

All these show that the focus is waaaaaaay too much on her. You're analyzing, making assumptions, making judgments, letting things get under your skin, trying to control... focus on you and forget about what she may be thinking and doing. First, it will help you boost your PMA to get off that track, secondly it will probably better your DBing efforts, because right now from what I read, you're not truly DBing if you're doing all this other thinking.

Meanwhile, as an engineer, I am wired to demand that things be correct and fit the correct pattern.

Well then, as an engineer, rewire yourself so that's not the case anymore. Have zero expectations as to what the "correct" pattern is.

She had me believing we were making progress up until Tuesday night.

Maybe you were. You make it sound as if she's out to trick you. That's you projecting onto her. You're blaming her for what you chose to conclude to believe from what was happening.

We ended up having a 2 hour convo, going down the same old paths. The very same things I admitted/validated repeatedly in the past came up again.

If you go down the same old paths, you'll get the same old results.

Nothing in your sitch is going to have an assist to help change for the better, unless you're just lucky, until you change first.