Mel Morgan was delighted when her boyfriend Pete popped the question on her birthday.
The pair had met at school and had been joined at the hip since they first got together as teenagers.
But Mel's sister, Carly, had been friends with Pete before Mel started dating him – and unknown to Mel had always held a grudge against her sister for 'stealing' her only friend away from her.
One night, when Mel was away. Carly got the ultimate revenge on her sister by sleeping with Pete.
The pair kept it secret for years but Carly drunkenly confessed one night after a few too many glasses of wine – and the sisters have not had the same relationship since….while Pete is still trying to win Mel back.