A 38-year-old married mother of two from Saugus is facing charges that she had sex with a 15-year-old boy. Heather Salines was released on $7,500 bail after pleading not guilty to aggravated child rape during her arraignment Tuesday in Salem District Court. The Salem News reported that prosecutors called the boy vulnerable because his own mother had died and he saw Salines as a mother figure. The prosecutor said the case came to light after administrators at a Saugus middle school learned that the boy had been showing another student nude photos Salines had sent to his cellphone. In court, Salines’s lawyer called it an unfortunate incident.