Simply replace the unfilled areas such as "" and "[date]" with your information.
Hey [first name],
This is a hard thing to say so I'm just going to say. I love you. I have for a while. Time doesn't even matter anymore, does it? I mean I feel full, whole, you know? I wish I could tell you in person. I hope you'll call me as soon as you've read this, no matter what you feel. Can you do that for me?
Thinking of you,