I thought Jane gave very good advice in this. The first husband is with someone else, now - there’s no going back. She’d just hurt the current husband too, and have 2 big mistakes behind her, along with further disappointment and more regret in the future.
Bury the regret and make the best of the bed you’ve made.
I am sorry, truly, for the pain you are in.
Wait....what? Who's the victim here?