it’s crazy to be busying myself with anything other than the relationship and not filing for D.
Filing for D is compatible with DB'ing, as long as you're doing it because you want that separation--consistently, many days in a row--NOT because you want to shock her or wake her up. If you have the emotional strength for this (rather than discuss, threaten, change your mind)--it makes sense.
You say it's crazy to focus on making yourself a better and more attractive person, that you should be focusing instead on this woman who's cheating on you with another guy. What would that look like?