Halanna

At this point there is no reason to be angry.

And it's less.

It was over a year ago.

Most likely he forgot the image was on his computer. He knew you would be using his computer while he was gone, if he thought there was anything on there he needed to hide he would have taken care of it before leaving.

Did he request the photo? If she sent it to him unsolicited, which is likely, he can't be blamed for what someone else has done, he has no control over what she sent, a year ago.

I would think after finding this you would have searched through his computer for other "evidence". Aside from the emails she is sending, you haven't indicated he is actively participating in this communication. It appears it's all on this other woman, and he has done nothing wrong.

So you can do two things. Confront him with, what, a year old photo that he probably forgot about?

Or, you can delete the photo, block her email address and forget about it.

In the future if he questions if you blocked her email, then you know he was looking for email from her, wasn't receiving, discovered the block and can open dialogue.

Otherwise you are creating an issue where presently none exists.