I know I have recommended these before but look for Calm for Kids Children's Bedtime Guided meditations on CD. They are awesome.
Well, she is only 8. That is still pretty young. You are having child number SIX---- where does she fall in the pack and do you expect too much of her? Something is really bothering her and from your post, you say it is around you. Could you perhaps relfect on your relationship with her and why she would always be upset around you? She may need more attention and she deserves it. It isn't her fault you have lots of kids----- I know you are stretched thin for time, but she sounds like she can use it. And she surely senses the "mixed " feelings you have. Try to find things in commen with her and try to enjoy her for who she is. Keep nighttime relaxing and calm and make sure you have story time with her still. Good luck.