Fear of Loss-I need help

Hello everyone, I just wanted to share my problem/ I really just need to talk to someone about this. If you read all the way through, bless you. In 5th grade, which for me was 8 years ago, a girl came to my school from Ohio. She was amazing, the first girl I truly loved. I remember getting on a swing next to her and asking, as our swings flew back and forth, "Hi, do you like Star Wars?" (Ever since my parents introduced me to Star Wars when I was a new born, ive loved it.) She said: "Yes!" I knew right away she was the one for me. Let's call her J. Throughout the year I got to know her better and better and fall deeper and deeper in love with her until the last month or so of school came along and I worked up the courage to tell her how I felt. She told me she felt the same way. I had never been happier in my life. So the last week of school came along and somehow, I forget exactly how, I found out she was leaving to move back to Ohio at the end of the school year. It didn't really phase me because I didn't fully realize what that meant( maybe I didn't want to). Anyway, the last day of school came and went. That night, J was having a sleep over at one of my good friend's house(also a girl) because J was leaving the next day. I arranged a surprize with my friend and during the sleep over I went to the house and gave a going away present to J. It was very classy if I do say so myself. I gave her a box that contained items that symbolized her favorite things. While she was looking through it, I handed her an ipod/headphones and played L.O.V.E. by Nat King Cole through it(i didnt have speakers). I still remember her smile. She handed me one of the headphones so we could listen together. We hugged and I stayed for a bit, then I got into the passenger seat of my mom's car(my mom helped me with the box and everything she is the coolest mom ever) while my mom was talking to my friend's mom, J came up said " Thank you for everything" and kissed me on my right cheek. To this day, that is the single most happiest moment of my life. Anyway, the next day came and my mom drove me to J's house to say goodbye one last time. We hugged and said our goodbyes. Then, she was gone. Out of my life. I cried the whole first week of summer. Even today I still struggle with the memories and have to fight back tears everytime I think back on them. Long story short, I'm in college now and ever since J left I've fallen in love twice but done my best to not get attached to either person and im sure it's due to a fear of losing that person after we bonded just like J. I actually did try a relationship with one of the two(lets call her K) but I didn't open up very much and I eventually broke it off not because I didnt enjoy the relationship ( I loved K with all my heart) but because I couldn't imagine what it would be like if we came together and were suddenly seperated forever like with J. I haven't told anyone the full story before. When I broke up with K I told her it was because I wasn't ready for a relationship. Sometimes I wish I would've told her the whole story but I didn't want to bother her with it because she was already going through a hard time in her life. Anyway, thanks for reading. Any words are appreciated May the Force be with you.