Please help me

This is a really weird story.. so I started dating my boyfriend when we were sixteen. The relationship got off to a really, really rough start. It just wasn’t good for anyone. It was my first time dating anyone, I didn’t know how to handle it. he broke up with me a few months after. And it wasn’t that he broke up with me, it was how he broke up with me? He did it over text, randomly, out of the blue, and it fucking hurt. I mean it really hurt. The way he did it hurt, the fact that he did it hurt. We got back together a few months after, and have been back together for another year now (so we’re going on two years) anyway, our relationship is great now. He’s my best friend. But there’s still a part of me that’s terrified he’ll just randomly leave me again. I’ve never really told him that, because I don’t want to freak him out, but it really does scare me. I told him about how I used to write about him in my journals, but the way I said it made the whole thing come out wrong and it was over text so it was even more awful and now I’m really scared I freaked him out and that it’s all gonna happen again. I don’t know if I should express that I feel this way to him or not, I really don’t know what to do.