<human>: Can you succinctly summarize the text in 1-3 sentences?

So this has really been stressing me out because I have no idea how to deal with a situation like this. This friend of mine was previously considered a threat to my relationship because my boyfriend had a crush on her before we dated. Eventually the girl and I became friends and I just recently (within the last 2-3 months) have been able to fully trust her and consider her a friend. However, a group of us spent the day all taking MDMA together, which makes people usually feel open and cuddly. Somehow she thought that it would be okay to send my boyfriend (of 3 years) a picture of her in lingerie. I as well as one of my friends saw her send the picture and I was also able to confirm with my boyfriend that she sent it. As for him, as soon as we got home, I asked about the picture and he told me that yes he had received it, and it was completely out of nowhere. He showed me his message thread with her without any problem, which was normal appropriate conversation, with this random picture thrown in. I told him to delete it which he did immediately with no problems, so really I'm not worried about him here. I'm really concerned with how to go about confronting her on this situation. I'm not a person who likes to create drama and I tend to avoid confrontation so I want to figure out how to do it in the most adult way possible.
<bot>: A girl I previously considered to be a close friend sent an unwanted lingerie picture to my boyfriend. He responded appropriately in my opinion. How do I go about confronting her on this?