I agree with Kelli.
On the surface, that's what you are saying, "it's about the pictures." However, it's quite odd, that you mentioned the pictures in the emails exactly ONE time, and the fact that you were upset about him selling the animal several times and even made a blotched attempt to pick up said animal.
I think you should be honest with yourself, you are ticked off that he didn't keep his word, and a little upset that he's using your pictures to help sell a snake that he promised to keep forever.
It may be all jumbled inside you and you may be justifying your anger..you are RIGHT to be upset about your pictures being used..but you (just from reading the emails) appear more upset about him selling the animal.
Let me say for the record, he should not be using pictures that do not belong to him to sell the animal. This technically could qualify as "misrepresentation" if the animal no longer looks like the image in the pics (weight loss, scars, illness, etc).