I kissed my cousin, what do I do?

I'm a 17-year-old male entering my last year of high school. My family consists of five people: my mom, my dad (who is my stepdad), my two brothers, and me. I am genetically related to everyone except my dad, who has raised me since I was two years old. He was born in Mexico and has a large family there, including my cousin Alexa, who is 19 years old. She came to visit us in Arizona, and since I had never met her before, I didn't think much of it.

During the recent 4th of July weekend, my dad had the day off work, and we all went downtown to see fireworks, except for my mom and my little brother, who had an unrelated commitment. It was a fun evening, and we even saw a famous person. The next day, Friday, we went to see a movie together, sitting next to each other and sharing food, which I don’t mind doing with people I know. It felt almost like a date. Later, I left to hang out with friends, so I didn’t spend more time with her.

Saturday was when things got interesting. We went to the river with some family friends and had a great time. At one point, someone asked if I was dating Alexa, not knowing we were cousins. We were just a boy and girl getting along well, and it seemed natural. Later that day, while swimming, I started to feel attracted to her, and I later realized she felt the same way. We acted like a couple in the pool, except for kissing and hugging, and again, we were asked if we were dating. We both laughed it off and said we were just cousins, which felt crazy to us.

That night, as we were leaving, an adult at the party tried to give me advice on how to "seal the deal" with Alexa, unaware of our relationship. My dad, who was standing behind him, explained that we were just cousins, and I sensed he was concerned about what might be happening. He wouldn’t let us sit in the back of the truck alone, which made me think he was worried.

The next day was Sunday, my dad’s birthday. Alexa made enchiladas for him, and while we were at the store, I noticed how much we looked like a couple. It felt strange, but I didn’t care too much. Time passed, and my dad left to celebrate his birthday with friends. My brother was home but passed out on the couch, so it was just me and Alexa watching movies. We ended up tickling each other, and things took a turn when she bit me. I have to admit, biting turns me on, so I bit her back, and then she licked my cheek. I knew it was a bit wrong, but I was having fun and laughing.

Eventually, we settled down, and she rested her head in my lap. I’m not sure what prompted it, but I gave her a nibble on the neck, and when I pulled back, we ended up kissing. It wasn’t just a quick kiss; we kissed passionately for at least 30 minutes. We were both getting exactly what we wanted, and neither of us wanted to stop. However, I realized how it would affect my brother if he saw me kissing his cousin by blood, so I told her we had to stop. She didn’t want to, and honestly, I didn’t either, but we had no choice.

The next morning, while I was watching TV, she came into my room, sat with me, and we held hands the whole time. I felt incredibly close to her, and I kept telling myself that it wasn’t wrong since we weren’t technically related. She has been gone for a full day now, and just as she predicted, I miss her a lot. But I can’t help but think about my family and my dad. How could I do that to him, especially on his birthday? I’m usually very picky when it comes to girls, and now that I’ve found someone I care about, I feel like I can’t be with her. She wants me to visit her in Mexico, claiming it’s so I can practice my Spanish, but I’m unsure if that’s the best idea. I care for her deeply, but I don’t want to risk my dad’s connection with his family for what feels like a complicated but amazing relationship.