Those statements "I knew we would be better off separated" is nothing more than your H justifying his actions to D and continue the EA, I might even guess that divorcing you is the obstacle to the PA if it has not gone that far yet... Either for him or the OW. This is normal, they are pursuing happiness that is drug induced at the moment, and typically its us The LBS who are perceived as the problem
What you do now, is what you've been advised to do, list some specific goals, do some GALs ... Pick something out of your comfort zone, try something new.... Let your H go for now as you work on yourself and become stronger... You can do these things and still honor your M. Trust me you will be better off for this growth in the long run