The mother of one of the 20 children killed in the Sandy Hook Elementary School mass shooting in Newtown, Connecticut, in 2012 slammed President Donald Trump on Sunday for “appalling lack of humanity and decency.”

Nicole Hockley, who lost her 6-year-old son Dylan in the massacre, ripped Trump for failing to acknowledge Thursday’s five-year anniversary of Sandy Hook, and for inviting National Rifle Association head Wayne LaPierre to the White House Christmas Party on the same evening.

Brendan McDermid / Reuters Nicole Hockley, the mother of Sandy Hook shooting victim Dylan Hockley slammed President Donald Trump for his “appalling lack of humanity and decency.”

“Not only did he ignore the five-year remembrance completely ― not even a single tweet ― he slapped us all in the face by having none other than NRA President Wayne LaPierre at his White House Christmas party that night. The appalling lack of humanity and decency has not gone unnoticed,” Hockley wrote in a Facebook post that went viral.

“While they ignorantly partied and remained uninformed on an issue that kills thousands of Americans every year, I was crying myself to sleep,” Hockley continued. “While they got the chance to kiss their children goodnight, I kissed the urn holding my beautiful boy’s ashes.”

Hockley was one of two parents who founded Sandy Hook Promise, a nonprofit that focuses on protecting children from gun violence. In an interview with HuffPost, Hockley said Dylan was the glue that held her family together.

“He had a huge smile and beautiful eyes, and everyone was so in love with him. He was an amazing little boy,” she said.

White House press secretary Sarah Huckabee Sanders confirmed to the New York Daily News that LaPierre was present at the White House Christmas party on the evening of Dec. 14.

“I’m not aware of a conversation between [LaPierre and Trump],” Huckabee told the Daily News. “He was there for a Christmas party and not a formal meeting of any kind.”