Write a short story about him, and your whole relationship. Make his flaws as your boyfriend subtle, yet noticable to the discerning reader. Make sure you thinly veil the underlying messages with obvious hints (i.e. if his name was Bill name his character Phil... or even better Brill, the less sense it makes the better). Have the story's rising acting point out his callousness, and cold-heartedness that leaves the tale's protagonist Betsy (you) to question her self worth, and her female identity. The denoument leads to Betsy taking control of her identity, and her sexuality in a Chopin-eseque turn of events that leads her to drift further and further out into the ocean until there's no hope for return, as Betsy finally overcomes the overbaring patriarchy of the world by taking her own life.

THEN call him up and read it to him while he's fucking your best friend. Dude, if MY ex-girlfriend called me while I was fucking her best friend.... I'd be PISSED! NO DOUBT! LOL!!!!!!!