The Fan (1982) review

Simone (Désirée Nosbusch), a teenage girl from West Berlin, is unhealthily obsessed with Ian Curtis-like pop star "R" (Bodo Staiger) and keeps writing letters to him even though he never responds, so she hitchhikes to find out where he's at, catches his attention and they become intimate ... but when he tries ditching her, she doesn't react in a positive manner.  The first half hour consists of an overbearing amount of voice-over from Simone as she does little else but fantasize about her object of affection and the score by Staiger is terrible, but it's all to set up the truly nutso last third in which "R" thinks he can pump-and-dump Simone but she retaliates in the most graphic way possible, smashing him in the head with a statue, dismembering his corpse, drinking his blood and then cooking him.  At the time of the shooting Nosbusch was only 16 years old and is completely nude for the sex scene - she later admitted she felt exploited but allegedly made peace with the filmmaker - which might alienate sensitive viewers ... but she does "win" in the end, so it could be seen as a perverse act of "feminine empowerment" (which is more realistic than unsupported interpretations it has anything to do with Nazi Germany).