How do you respond to a sincere/heartbreaking letter?

some people have told me that this guy was leading me on just to get help with debate. i started to believe them because it really did seem like it. so i decided to be straightforward and ask him. i told him it was okay if he was, i just wanted to know. he emailed back saying that he was not leading me on, hes not that kind of guy, and that i hurt him since i accused him. he also talked about not going out with me since he didnt really know me and all. now i feel very very bad about what i did. and honestly i dont really want to like him anymore. i just want to stay single and focus on school and such, but its really hard to. what can i say back in apology and show him that he doesnt have to worry about me liking him? but mostly, i dont know how to respond to something like that, please help!! and thank you!