カナディアンの女友達に恋愛相談をしようかな・・と思っているのですが、彼氏いるの？と相手に聞かれて、彼氏はいないけど「気になる人」もしくは「一目惚れしてる人はいる」と答えたい場合、どのように英語で言ったら良いでしょうか？

I don’t have a boyfriend, but I like someone a lot. I fell in love with him at first sight! ^^ 　

I have someone in mind.

> I fell in love with him at first sight!
You can say this only when you are together with this guy and telling someone how you get together with him.
If you say this when you have a crush on this guy(you’re not with him), it sounds like you are a stalker :o
　

I don’t have a boyfriend but I have a huge crush on somebody.

Agree with Res2. You don’t want to say "you are in love" or "you fell in love" when there is nothing going with the guy. It sounds bit crazy.

Hope you would be in love with a guy you like!