Some more info:
Me: 38, Her:28
Married: 1.5yrs, Together: 4yrs - Almost inseparable the whole time.
No kids. She changes her mind frequently on wanting them.
She met the guy after we separated. She's also dated others, and took a 2 week vacation by herself to escape all the stress this ordeal was causing her. I've dated others too, but I'm basically just going through the motions because all I can really think about is her.

She's also expressed that maybe she never wants to be married or tied down at all again, and she might be polyamorous. Her lifestyle (other than her career) has had a couple complete 180's, where she jumps in with both feet and then later reverts back. Whereas I'm open minded, but much more slow and cautious in general.

As far as Sandi's rules: I pretty much did the exact opposite of that for a while, and have gradually moved to following them over the last 2 weeks. I have to say, it seemed to improve things. It's a real leap of faith to follow them though. I know I should stop initiating all contact with her, but I really want opportunities to show her how I've improved. And I really don't want her to become more attached to the guy she's dating, though that's likely out of my power.

I know she's conflicted, but I'm starting to believe her when she says "it's too little, too late".