Teenaged dating

So I need your guys’ advice. My best friend likes me, and I like him, but I’m nervous about the emotional side of it. I’m only 13, and he’s 15. We talk to each other every day, and we know everything about each other. Also, we only found out that we liked each other yesterday and he already wants to ask me out!!! I tend to think into the future, and I’m already thinking about our friendship, or lack of it, when we inevitably break up. Please help me!!! I’m super nervous.