Help I don't know what to do?

Okay, so last month a friend of mine convinced me in going to this nudist beach. I am not a nudist myself and this was to be my first time going. I thought that I would get an erection because of all the naked women so I was hesitant, but my friend said I wouldn't because everyone else would be naked. Anyways I was still a bit uncomfortable but I didn't want to let my friend down. Anyways it is a family-oriented place so parents can bring their children and stuff. At first everything seemed awkward but then I started to relax because everyone else was naked too so surely no one would make fun of me. The problem didn't come until later when my friend asked me to join this water football game. The resort was at this beach and my friend and I joined in this water football game. I asked my friend how we were supposed to tackle and he just said to grab the person's arm and drag them down or push them from the shoulders or back to advoid contact with the genital areas. Well, we were in the water and it wasn't to bad I would just like push a kid down or drag them down by the shoulder. We were in water so it didn't hurt to get tackled. Well anyways it is hard to keep your balance in water so during the middle of the game I went chasing after this person and I tripped over another guy's ankle and fell right on the back of this girl who had to be like fourteen or fifteen. I felt so embarrased so I got up immediately and apologized but I was pretty sure my penis had just rubbed up against her butt area so she just gave me a funny look. She didn't even say like"Oh no problem or "things like that happen". I think she feels violated. I tried telling her it was just an accident but she didn't say anything. I keep thinking about it. Should I call my friend and see if she can tell the girl or her parents it was an accident? do you think she remembers? I feel so stupid.