What is DV? A Driving Violation? Bad enough to be arrested for?

Ask the attorney about more time with the 2.5 year old. I assume the 8 month old is being breastfed, and that puts limitations on how long you can stay with him. To the best of my understanding, courts honor and respect the needs of breastfed infants - the needs for close proximity to mom most of the time. But the 2.5 year old is old enough to spend long spans of time with you. And make sure the attorney gets some kind of a clause into the agreement that would allow for revisiting the issue of visitation as the baby gets older and stop being dependent on breast milk. If your wife breastfeeds past the first year, night feedings should suffice - you can ask to have him for a whole day -- you will be feeding him table foods or baby foods.

I think you should also tone down the negative self talk - you posted about your "horrific choices" - it seems that you made a bad choice once. I do not see a multitude of choices to berate yourself for - you tried your best to get through to her, and, given that you had been dx'd with BPD before you got married, the "in health" part of the vows was blatantly not upheld by the wife, since she knew that she was marrying a person who might need joint therapy sessions. Had you been dx'd with BPD while already married, we could speculate that she was not able to adjust because of the shock of the diagnosis or whatever, but no, she knew what she was getting herself into - you said that you had counseling pre-marriage, so I assume that she was fully aware of your mental health issues.

You speculated that she might have BPD traits herself given the black-and-white thinking. Could be, for sure. That might explain the drastic reaction coming from her. Another hypothesis is that she used the opportunity to get rid of you, hence the drastic reaction without any shade of doubt, hesitation, or regret. I am leaning in favor of the latter hypothesis, because you said in the OP that she just is not an emotional person. A person with BPD would manifest the BPD in the course of day-by-day living, and not just when presented with an extreme stressor. Sure, the stress would trigger a BPD person, but not from 0 to 10. Say, a BPD person would have symptoms at 3 during peaceful times and symptoms at 8 during stressful times - it is a matter of degree. Per OP, she was quite unemotional before the affair happened. Also, there was no push-pull coming from her. Read this:

Out of the FOG - Push-Pull Behavior

Apparently this is common in BPD. She did not display any of it. I do not know if a sudden onset of BPD in response to a stressor is possible; you might want to discuss it with your individual counselor.