This is my first thread ever but I could use some advice

Last year I started crushing on "jake". He was really shy but I got to know him through track and we became pretty good friends. Over the summer we spent time together, which was a big step for both of us(neither of us ever being in a relationship before). The last time I saw him over the summer it felt really uncomfortable and weird. After that I started to lose interest in him as more than a friend. When school started I still kind of liked him, but soon lost any interest I had left. We still hang out and I know he still has a crush on me, but I've started to crush on someone else. So my question is: what do I say to jake? I want to hurt him as little as possible, but how do I do that?