AITA for refusing to go outside after I catch my GF's best friend trying to get a pic of me nude?

I'm 24 and my gf is 22. We've been together for almost 4 years now. She has a friend she grew up with and they've known each other since the 1st grade. I'll call her Kelly. Kelly is a nice enough girl but I've always thought it was a bit weird how she reacted towards me. She was obviously blushing a lot, always looked at me smiling, I even caught her crying once when I brought flowers home to my girlfriend. And straight up just staring for no reason. Even after getting used to her and the way she acted, I thought it was a bit too much. But she was a childhood friend so I just rolled with it.<br><br>In case it's important: I'm kinda hot. I know it sounds arrogant but a lot of people have told me that and it's nothing I really like to think about or use to my advantage. It just is what it is.<br><br>Last week, Kelly and her boyfriend were going to be in our city for a couple of days because of something with her work. My gf suggested we could all go camping together as a little friendship thing. I was like "sure, why not" since I like camping and figured it would be a bit of a fun experience. So we got everything set up the day before and all we had to do that morning was pack all our stuff in our cars and take off. I woke up early to get some of the packing done, I'm a very organized person and like to know my time frame.<br><br>So we were all still in our apartment that morning. The plan was to leave at 10am, so obviously we were still in our morning clothes, so whatever. I go to take a quick shower before we leave so I can feel refreshed and all that. I walk out of the bathroom and Kelly is holding her phone and has a very red face. I go "hey" and she goes "hey" back and I go about my day like nothing happened. But when we're in the car, I see her boyfriend hand her a phone in the backseat and she has a red face again. That's when I notice the screen on her phone. It's a zoomed-in photograph of me that they took when I was walking out of the bathroom...naked. I started feeling extremely creeped out and I tell them all we can't go camping because I'm not feeling comfortable. Kelly starts going on about how it was just for fun and they didn't mean to hurt my feelings and how I shouldn't make a big deal out of it. I go "how would you feel if I took a nude of you?" and she just says "please don't do that" and starts crying. I grab my stuff, including my tent and all camping gear, and drive back home.<br><br>I haven't talked to my gf since that day. She texted me saying I was being a dick and ruining her trip with her best friend and that I should "man up". I told her I had no intention of talking with her again at all and that she has no right to say anything to me. I feel like I really don't even want to see her or talk to her again based off how she reacted to the whole thing but I also don't want to just end a 4 year relationship like that.