Should i tell her how i feel or keep trying to forget about it?

I really fell in love with the first girl I kissed almost 4 years ago. I have had other relationships but I still feel the same, like something wasn't finished. I never really got to tell her how I felt and now we live on different sides of the country. I really think she is a special person and now I might not see her again. I think it would be inappropriate to say anything at this point, but I also can't move on. I have tried writing letters but can't bring myself to send them. I'm not sure what's wrong with me. What should I do? (FYI I still text with her once a year or so, just small talk)