If someone has sex with you when you are BLACKOUT drunk, as Peter was, THAT IS RAPE. There is NO ROOM for debate on this score. If you're too drunk to even REMEMBER what happened, then you're too drunk to CONSENT.
I'm actually being CHARITABLE by calling it MUTUAL rape, because if Michelle remembers what happened, and Peter doesn't, then that means that SHE raped HIM, which makes all of her rage at him after the fact INCREDIBLY morally wrong, ESPECIALLY since it's being played for comedy.