<human>: Condense the text into a few key points

So I've been dating this guy for over two years now, Isaac, and we've had some issues in the past when I found him making fakes of celebrities. I found it disrespectful to me and the women who's photos he was editing. It's been a while since that, and I think it's stopped, although who knows, maybe he just became more cautious about it. 

Being honest here, I was snooping on his computer today and found an image of a girl with her ass to the camera. Did a reverse image search but wound up with no results. I was pretty certain that I knew her, went to her IG, and low and behold, I found the photo. However, the photo that Isaac had of it the background had been cropped out. 

Now, for a little more context to this girl. She's dating a good friend of Isaac, who he was into while in high school. They never became anything because she's a lesbian. If she knew that he did this, she would be as livid as I am. I guess I'm just super repulsed because this crosses all lines and need some help from you guys. I'm really sorry if this is a mess, I'm just super devastated right now.
<bot>: My BF has a sexy photo that he edited on his computer of a girl we both know. What do I do?