How do i get my boyfriend to break up with me?

a guy that i liked asked me out a couple weeks ago and i said yes (of course). but since then, hes been really obsessive and awkward. i want to beak up with him, but he is suicidal. he told me that when he asked me out, he had a razor in his hand just in case i said no. when his ex broke up with him (because of the same reasons), he almost killed himself, but his sister walked in right before he cut his neck. i really don't want to hurt him, but i don't want to go out with him anymore. how can i make him break up with me?