Jeri,
Being a mother is the hardest job you will ever love. In a day and age when children are not as respectful as they used to be, and society to does not think you are successful w/o a career makes that job even harder. Being a single mother makes it that much harder. If you have been divorced since February, 2007, it has been long enough that I do not think the issue has anything to do with the fact that she is not adjusting to change.
Being a child is hard. Especially now that kids do not get to come home after school, they have day care and other things to do instead of find comfort at home. I think that change is hard for kids and you need to pick what is imprtant to you and try to change one thing at a time. If you want to work on the sleeping in there own bed thing work on that for a few weeks, and when you get that down, which you can, then move on to the next thing which is her respecting you and your guests.
The kids getting in your bed. Talk to them about it, talk to there father about it and make sure that when they are at his house he is setting the same rules you are. When they come into your bed you have to get them back into there bed. If that means you set up baby monitors so you can here them and close your bedroom door, set something up so that they make a lot of noise when they come into your room. You need to be awakened when they climb into your bed and you need to put them right back into there bed. Tell them they are suppose to sleep in there bed. I have talked to parents who have told there kids they are not suppose to get out of bed, but they are suppose to call mommy from the baby monitor and she will come. If you can get them used to not gettting out of bed and going back to sleep in there bed you will be home free. It will not be easy, and you will loose sleep for a few nights, but if you stick to it you can do it.
As far as her disrespecting you and your guests, you need to solve this problem before her brother thinks it is OK. If she does not want to participate in the activity at hand I would send her to bed, you don't want dinner, bath pj's and bed. Do not give her attention for negative behavior. Seperate her from the situation. You have to give her attention though that is obviously what she is searching for. I would make Monday night we do what you want to do, but Tuesday night is mommy night and I want you to participate in mommy night, but you have to be respectful, or you don't get to participate. Wednesday is brothers night and we are going to do what brother wantes to do, and we want you to participate and you have to be respectful to brother. Include her in things that allow her to feel like she has control, but make them things that you can handle. On mommy night we can have what you want for dinner and you can help me cook. Make her feel important, but make her earn attention for positive choices.
I saved the best for last and I hope I did not loose you with all I said, but you have got to talk to her daily about hurting herself. Make sure that was just a cry for attention, and that she is not serious. Do not be affraid to ask for help outside of the message board. That is something that is very serious. Reaffirm her as often as you can, and encourage dad to be a part of this as well. Make sure he is reaffirming her daily, phone calls, notes, whatever it takes!
Good Luck and I will keep you in my prayers.