Facebook threat...possibly help my case?

my ex told me his new gf’s name, so i looked her up on facebook. she has a completely public profile and i was shocked at something i saw and read. there was a pic of her in lingerie, and my ex had his right hand on her rear and the other hand holding a gun. below he had commented, any dude f-word with my chick and last sound theyll hear will be my gun loading. this really disturbs me and i dont want that around my children. if i try to use that will it be considered privacy invasion or could it be valid because its a public profile?

You have not stated how you would use the information you pertained, but if you obtained the information because it was a public profile, she should not be able to maintain an action against you for invasion of privacy.