I was in a similar situation. Someone confessed to me, and even though I liked him too, my last relationship had been really bad. I wasn't sure how to be in one again, and told him that I wasn't ready. I was scared that this decision, my rejection of hin, would ultimately change our friendship dynamic, or he'd withdraw from me, but he didn't. He didn't change at all. Didn't treat me differently. Didn't push. A few months later, I initiated conversation with him, and we're together now.

It's scary. I was terrified of losing this person who made me laugh every day. It had a happened before. I think that if he is worth it, he will think that you are worth it, too. If it was meant to be, he will wait, and treat you kindly. First and foremost, you need to be ready and at peace with yourself.