"My Mum said I had to call and let you know that I'm not coming home. My girlfriend had our baby this morning and I'm going to take [our son, who was 5 at the time] to meet his new sister!"
He'd taken our son out for the day, leaving our 13 year old daughter and me to have "a girly day". He called 20 minutes later, having been told to do so by his mother. We'd been together since we were 14, having known each other since the age of 11. We were 31 at this point. Our son developed a phobia of hospitals (because he didn't really understand what was going on, nor what any of the life-saving machines in a SCBU are for... and no one - his father, his paternal grandparents, nor the OW and her family - bothered to explain to the very confused little boy what on earth was going on), and our daughter's not spoken to my ex since that day... which was almost 10 years ago.
It also came out, a few months later, that he'd used our daughter's baby photo to pick up girls on his travels (whom he'd then have sex with), by claiming that I'd not let him have anything to do with her. They felt sorry for him... and I guess, slept with him to make him feel better. I often wonder about those girls and hope that they discovered their dignity and self-respect somewhere along the way over the last 21 years.
And when he married the girlfriend who'd given birth to his baby? 6 months later? Our son was invited... but not our daughter! They didn't want a sullen teen spoiling their big day - and, I suspect, figured that she was more than likely to tell everyone what a shit he actually is. Our son, on the other hand, was "too little to understand what was going on" and would have been used as a wedding prop for "happy families" style photos. Understandably, I said "fuck off!" and we went to a family-friendly music festival on the day with very good friends. Where my son very tearfully/innocently asked if I was still going to be his mummy now that daddy was making [girlfriend] his mummy, too? Two friends may literally have had to sit on me to stop me from leaving and gate-crashing the wedding, at that point, just to punch the smug fucker in the face and suggest to the girlfriend that she run for the hills before it was too late (and yet he wonders why our friends from school are now my friends and won't touch him with a 10-foot bargepole! He went from being the life and soul of the group... to billy-no-mates, overnight!)
The baby who was in SCBU is one of the most adorable little girls on the face of the planet, with a mischief maker for a little brother... and a mother who now she knows not to stomp on my boundaries when it comes to my children, is actually one of the best women I could have hoped for, as their stepmother. She does her best to include my daughter (who still refuses to acknowledge any of them - even the innocent children!), and I hope understands that as far as I'm concerned, she's more than welcome to the fucker who was my ex/is her current husband!