I thought that in order for IM's e-mails ect. that the courts determined that the SERVER owner is the person who must present them in to evidence. although that does not prevent him from using them in cross or trying, you have to challenge the validity and disclaim them.
You should keep copies of what you IM with your daughter so you would have a different copy to at least discredit his.
What btw did you say, maybe from his persective it was wrong of you?