Just saw your response.
If I knew what state you were in I would look for case law where FB was admissible.
Because I don't, I hope this link offers you and her some help.
It seems that lack of authentication is the only time it's been deemed inadmissible.
For those playing catch up.
Answer by fiatpax at 8:48 PM on Sep. 21, 2013
Next question overall
(Just for Fun)
Did you plan an outdoor wedding? If so, did it rain?