Don't know if it qualifies for a 'horror story', but the 1 guy I dated before I met my (now) husband was separated from his wife - until they got back together.
Of course he didn't tell ME they had gotten back together until a couple of months AFTER the fact.
On the plus side, the man I have been happily married to for 6 years now was introduced to me by the creep while we were still dating - they had known each other for years. :)
"Don't know if it qualifies for a 'horror story', but the 1 guy I dated before I met my (now) husband was separated from his wife - until they got back together."
Wasn't the fact that he was separated (not divorced) a big red flag for you?