Is "I love you" or "I have loved you for a long time" better?

I’m trying to work up the cajones to talk to this gay guy I have been in love with for years, and I’d love some Jelly advice on how to do it. I first met him four years ago, and he made me realize I could love men. I don’t think he had any idea (we were just buddies and he thought I was straight as I had a girlfriend at the time). We fell out of touch and I figured I’d never see him again. I haven’t been suffering about it or anything, but I never stopped loving him.

Well, we just got back in touch and we had a wonderful night recently, talking and drinking til 5 am. We were both very happy to see each other again, and he wanted to know when I’d be back in France, and whether he could visit me in the U.S. And he kissed me on the neck as we parted (although he might just have been drunk and had bad aim…). I think he’s been flirting with me via email, but it’s hard to tell with cultural differences/linguistic ambiguities.

I’ll only be here for another month and I don’t want to live with regrets. I won’t be devastated if he doesn’t share the same sentiments, but I won’t feel right with myself if I don’t tell him something. I don’t think it will ruin our friendship if it turns out it’s not reciprocal.

Would it be less creepy/intimidating for me to simply say “I love you” or to give him some back story and tell him that I have been in love with him for years?