You have all been through a lot of Trauma with the seperation, are you sure it wont work sometimes it is not to late you could get counseling for the fighting ,It is always good for Families to stay together if they can have you really worked on it?You daughter is sensitive and this has been very hard on her and the others, along with a dear pet passing ,and a new school it is not surprising she is acting up.If she is close to her Dad make sure she sees a lot of him, Dads are very important in their childrens lives and even if you dont live with him ,it would be the best thing for them to see him regularly,by comfort I think he also means attention and he is correct ,lots of positive attention for her and one to one time, get her involved in outside activities and sports keep her busy,when you ask her to do something give her the reason and ask her more than tell her, win over her co-operation.Most times all children neeed is care and love and they thrive, Good Luck