Traveler - I appreciate you actually reading up on the subject. You now know more than 99% of Catholics. And I completely agree with you that its complex and nuanced.
The first passage I found, in a book that was recommended here, was 1 Corinthians 7:15 that gave me peace.
This was in a Dobson book called "Love Must Be Tough". In it he talks about letting a spouse walk if they walk and knowing you can have / will have peace. That was actually big for me. It helped me to let go.
