I fucked my friend, now he wants a relationship?

Okay so ive known this guy for over 5 years and weve kissed before, but now we finally had sex...and the first time was good but the second and third time i just wasn't feeling it and actually regret doing it... i dont really want a relationship with him, when the sex happened we were both drunk. But he texts me all the time wanting to hang out and obviously have sex again but i just don't want to.

How do i tell him this?