Ruined Facesat Slave

My slave is ordered to worship my armpits while I tease his cock.  When he doesn't lick properly he is punished with very hard faceslapping.  I spit slowly into his mouth and slap him many times through this video.  I decide to facesit him to see how long he can last without oxygen.  I accidentally let out a big fart and make him swallow that too.  What better to way to reward this slave than to ruined his orgasm?