This is a photo of my husband and I. This is a photo of my husband and me. Which sentence is correct?

The pronoun I may never be used as the object of a verb or a preposition: This is a photo of ( my husband and) me.

The rule is to ignore the 'my husband' bit and imagine you were talking about yourself. So you would say "This is a photo of me" and not "This is a photo of I"

so the correct sentence is "This is a photo of my husband and me"