I just met my girlfriend's boyfriend.

I'm a 34-year-old man, and I recently met my girlfriend's boyfriend, who is 24. Here’s the situation: my girlfriend graduated from college today. Yes, there is an age difference between us, but we’ve talked about it, and she’s comfortable with it. We were introduced by a mutual friend who is 26. A little background: I've done a lot of work on myself regarding childhood trauma, relationships, and trust issues stemming from my upbringing in group and foster homes. As a result, I’ve focused heavily on communication in our relationship, which we sometimes struggled with. She had mentioned that her friends and family were in town for her big day and that they would help her move out of her apartment. Since her graduation was a ticketed event, I couldn’t attend, and we had agreed that I might not see her while her family was visiting. I didn’t consider this a red flag, as I’ve worked hard to not impose my past trust issues onto her. I wanted to surprise her with flowers, so I called her to let her know, but there was no answer. Thinking she would be at her celebration, I decided to drop off the bouquet anyway. When I arrived, I was surprised to see lights on and people around her apartment. Dressed up and holding the flowers, I knocked, and a guy opened the door, looking perplexed. I asked if my girlfriend was there, and he went to get her. When she came out, she looked extremely displeased, almost as if she had seen a ghost. I was confused because I thought she would appreciate the flowers, especially since I had helped her pick out a nice dress for the occasion. We exchanged words, and she was upset that I had shown up unannounced, while I was simply trying to be a supportive boyfriend. We agreed to discuss it later. As I was leaving, the guy who opened the door and I ran into each other. He revealed that he was her boyfriend, and I introduced myself as her boyfriend as well. Both of us were shocked. He asked when we had last been intimate, and I told him it was just two days ago, right before he arrived for her graduation. We exchanged numbers and agreed to sort everything out later. TLDR: My girlfriend has a boyfriend from her hometown, while I’m her boyfriend in the city where she currently lives, and we accidentally crossed paths in front of her family. Now, I’m unsure of how to proceed. Should I seek closure, or should I confront her? I really like this girl—it felt like a love-at-first-sight connection. Initially, I attributed some communication gaps to my own insecurities from past problematic relationships. I feel bad for the guy, as he was completely unaware of my existence. They were supposed to spend a long weekend in the mountains together, which she had originally described as a "friends trip." We had discussed the challenges of long-distance relationships and made plans to see each other once a month, as well as move together to a new city in six months. However, I’m at a loss. The guy and I have talked briefly, but she hasn’t responded to my messages. He did mention that she admitted to him that I exist. I'm frustrated, especially since she shared her past trauma and trust issues with men. I’ve genuinely tried to meet her halfway and help her overcome her beliefs about men, only to find myself in this situation. It’s disheartening. 😫🤦🏽‍♂️