By Eric Levenson and Celina Tebor, CNN (CNN) — “I’m sorry, mom.” Those were the words Colt Gray texted his mother Wednesday morning before the deadliest school shooting in the United States so far this year erupted at Apalachee High School in Winder, Georgia. That text was enough to spur a call from Marcee Gray to her son’s school to warn about an unspecified “extreme emergency.” Marcee Gray spoke to a school counselor for about 10 minutes, Cha…