I kissed my cousin, what do I do?

I’m a 17 year old male going into my last year of high school. My family has 5 people in it. My mom, my dad, me and my two brothers. I’m genetically related to everyone except my dad (step-dad). I call him my real dad because he raised me since I was 2 years old. He was born in Mexico and has lots of family there. One of which was my cousin Alexa who was 19 years old. She was coming to Arizona to visit us and I didn’t think much of it since I had never met her before and she wouldn’t be here long. It was the recent 4th of July weekend so my dad had work off and all of us (except my mom and my little brother for an unrelated reason) went to go see fireworks downtown from where we lived. It was me, my dad, Alexa, my older brother and his girlfriend. We had a lot of fun and even saw a famous person so it was pretty great. The next day was Friday. In the morning we saw a movie and we sat next to each other and shared food (I don’t mind sharing food with people I know). It was almost like a date. Later I left and went to hang with friends so I didn’t hang with her. Saturday is where things got interesting. We went up to the river with some family friends. We had lots of fun and the first person to ask me if I was dating my cousin Alexa had asked. He didn’t know we were cousins (like anyone else) because we were a boy and girl who got along great and were kinda close. Later that day we went swimming (my dad didn’t wanna miss a pool party). I started to become attracted to her and I didn’t know it at the time but so did she. We acted like a couple in the pool (except for kissing and hugging) and was asked by some kids once again if we were dating. This was the first time she had seen someone do this. We both said no and said we are cousins and that would be crazy. Then we were leaving that night and one of the adults at the party was trying to give me advice on how to seal the deal with Alexa. He didn’t know either. My dad was standing behind him and explained to him that we were just cousins. That was when I began to feel he feared what might be happening when he wouldn’t let us sit in the back of the truck alone. The next day was sunday, also my dad’s birthday. She made enchiladas for my dad and when we were at the store getting food I noticed that we really looked like a couple. It was weird but I didn’t really care that much. Time passed and my dad was leaving to go celebrate his birthday with his friends. He’s always late so we had the time. My brother was home but he was passed out on the couch on the other side of the house. Me and Alexa were watching movies. Actually we watched about 10 mins of the movie and spent the rest tickling each other. Things became strange when one of the times I was tickling her she bit me. Now, not to be weird but biting turns me on. So I started biting her back and then she licked my cheek. I knew it was kinda wrong but I didn’t care, I was having fun and laughing. Eventually we kinda settled down and she had her head in my lap and I don’t know what finally pushed one of us to make the move but I gave her a nibble on the neck and when I started to back away I moved towards her face and we kissed. Not for the entire time but at least every minute for at least 30 minutes we were kissing. It was very passionate. Both of us were getting exactly what we wanted…each other and we didn’t wanna stop but I realized what it would mean to my brother if he saw me kissing his cousin by blood (he was my stepdad’s actual son). So I told her we had to stop. She definitely didn’t want to stop and I didn’t either. We had no choice though. We stopped and went to bed. The next morning I was watching TV and she came into my room, sat with me and we held hands the whole time. I felt so close with her and the only reason none of it could be wrong was because we weren’t related technically. She has been gone for a full day now and just like she said I would, I miss her, so much, but what about my family? What about my dad? How could I do that to him and on his birthday? I’m the pickiest guy in the world when it comes to girls and when one is finally found…I cant be with her. She wants me to come visit her in mexico (her excuse is so I can practice my Spanish more) but I’m not sure if its the best idea. I care for her very much for sure but I don’t know if I wanna risk my dad’s connection with his family for a twisted but amazing relationship.