She may think its ok, but you have to remember that its not ok. Its adultery. Its horrible. Deep down, she knows it but these WAS love to twist history and justify what they are doing. Remember: adultery. Separated? Yes. Still legally married? Yes. Adultery = wrong.
But...I think how you handle it depends on what you want from the situation. I knew about H's A before he confessed, its horrible. I didn't sleep more than 20 minutes at a time for quite awhile. I feel for you.
I think its good you are getting your head together before you decide what you are going to do. Take care.