Its a comedy horror genre where the mc wakes up to find that he accidentally killed his be...

Its a comedy horror genre where the mc wakes up to find that he accidentally killed his best friend who his gf was cheating on him with. The manga is basically him trying to get rid of the body without getting caught.There's also a side story about another character who is a serial killer(?) Or a psychopath(?)who dresses like the police and encounters the mc. Im pretty sure the psychopath kills the gfbof the mc as well. Pls help me find this manga （/TДT)/ I've been looking all over for it.