Nudist beach

So, I was always throwing the idea of going to a nudist beach with my girlfriend just for the experience. I was pretty confident in my body. Quite fit, average at best penis (for context later). So, we did go eventually. A couple of days ago. We were having fun, beautiful day. It was kind of weird when we took our clothes at first but after a coule of minutes, it was alright. At one moment, another couple? probably, could be friends, came and sat fairly close to us. I didn't day attention much, I was lying down. When my gf noticed them though, she repositioned herself and used her elbows to support her weight. Again, I didn't notice anything weird. After a while, everytime I looked at her, I see her head is facing their way (with sunglasses on). And when I look I see why. This guy let's say, he was impressive down there. Let's just say his soft penis was quite longer that my erect. I died inside. I felt my stomach weird. It couldn't be. I knew she wasn't that shallow. But I stared at her from the side of her sunglasses to see where she's looking at and my suspicions were correct. I knew she was making comparisons in her head. And things get worse. When she turned around to look at me, first thing she looked at, was my penis. She was definitely comparing. I haven't talked to her about it, and please don't tell me I should speak to her, I just want to get it off of me. I feel awful. I feel like she settles. I used to feel a little small sometimes, other times average, but now my confidence is ruined.