As a daycare provider and a mom, I don't condone co-sleeping, especially at this age. She does need to learn to quiet herself. But 8 years old is a tough age for a child to be able to control herself. I might lay with her in her bed, tell her it will be for 10 or 15 mins, and then she needs to sleep on her own. Or maybe start even farther and say you will stay till she falls asleep for 1 week and the next week stay for 30 mins and the next 20 and so on.??? Definitely need to be on the same page with Dad though, I would consider family counseling to help come up with a healthy routine you both can follow.