A leading young Democrat and de Blasio administration employee has a secret taste for sickening kiddie porn that involves baby girls as young as 6 months old, court papers revealed Friday. Jacob Schwartz, 29, was busted for allegedly keeping more than 3,000 disgusting images and 89 videos on a laptop after downloading the filth from the internet. The illegal smut shows “young nude females between the approximate ages of 6 months and 16, engaging in sexual conduct… on an adult male,” court papers say. Schwartz’s father — labor lawyer and Democratic insider Arthur Schwartz — called his son’s case “a personal tragedy.” “I understand these are serious charges,” said the elder Schwartz, who watched his son get arraigned in Manhattan Criminal Court on Thursday night. “He’s already in therapy for…