My cousin accidentally sent me a video of herself masturbating. I'm gonna see her in person in 2 days. What's the least awkward approach possible?

My (28M) cousin (20F) has a boyfriend with the same first name as me, same spelling. They've been together for about a year-ish and over the past year she has frequently sent me texts meant for him. Most of the time it's menial things, random bits of conversation out of context, never anything bad or inappropriate. It's an understandable mistake and she always says "Sorry" or "Whoops, wrong [my name]".

Only once before a couple months ago did she slip up and send me a wrong image and it was a photo of her in lingerie in a store changing room with a sexy caption meant for her boyfriend. She's worn bikinis around me in real life before so it wasn't anything I hadn't seen before in terms of partial nudity, but it was nonetheless at that point that I had to tell her to please be extra careful with which [my name] she is sending texts too and she said she will be more diligent in the future. She apologized and we moved on. Sometimes though, we do legitimately send each other memes or other funny things back and forth and getting a photo or video from her every now and then is not abnormal. We also both watch the TV show The Bear and will text about it whenever there are new episodes out. As "the older cousin" that's pretty much the extent of our relationship.

The past few months she has been very good with not sending me wrong messages...until now. Yesterday morning very early in the morning I received a text from her with a video. The video thumbnail was just a wall and a stool and the text caption said "Good morning :)". I assumed it was a meme or some other weird funny video so I pressed play and it turned out to be a video of my cousin completely naked, sitting on the stool, spreading her legs towards the camera and masturbating herself with a vibrator. I obviously clicked off as soon as I put together what I was seeing but I still saw everything. Crystal clear HD phone video taken in bright lighting. Unlike the previous instances there was no message afterwards saying "Sorry" or "Don't watch that video" or anything of the sort. Just the video of her naked masturbating and total radio silence since then.

I have chosen not to respond in any way because I think any response will lead her to assume that I have seen the content of the video, which is, in fact, true.

I have 2 assumptions of what happened. 1) She tried to unsend it or cancel send as fast as she could and thought she was successful, not realizing it already went through on my end. This would explain the lack of a follow up. Or 2) She knows she sent it to me and is simply too mortified to say anything about it at all, which is completely understandable. This seems like the more likely option, but I can't know for sure. I know she has been on her phone because she has been actively updating her Instagram story and she looked at mine that I posted later that morning, but she has not said a single thing to me directly.

I am supposed to see her in person 2 days from now for my other cousin's (her older brother's) wedding, who I am pretty close with. I assume her boyfriend will also be there since he's usually with her at family functions. To be honest, if this happened with a cousin my age or older I probably wouldn't care as much, but she's been a kid for as long as I've known her up until a few years ago and our relationship is like that. If she does know she sent it to me, all of this will add to the awkward factor. She is an adult now but I have always thought of her as one of my kid cousins and now I've seen her masturbating and she probably knows it. If she doesn't know she sent it, then I guess nothing will happen. But I don't know if she knows.

What's the safest course of action? I don't want to confront her about it directly in person and risk a really uncomfortable conversation around others - especially if her boyfriend doesn't know - and I also don't want her to avoid me all day and keep it awkward between us forever, which could be the case if I say and do nothing.

I have no idea what to do. Has something like this ever happened to anyone else here? What did you do?

UPDATE Sunday 9/8/24: We avoided each other for most of the ceremony but afterwards during the reception we met waiting in line for food and she actually apologized without me having to say anything. She asked if me I saw the contents of the video and I said yes. She was mortified but acknowledged it was her wrongdoing and I made sure she changed my contact name to something more distinguishable. We both agreed never to speak of it. Her boyfriend doesn't know.