The inquest heard that Demi discharged herself from the Grange University Hospital in Cwmbran on the morning of 12 February, having attended the previous evening following a suspected overdose.
Shortly before 12:25 GMT, she left the hospital with a support worker – but stepped out from the central reservation of the A4042 into the southbound lane. Demi was hit by vehicles.
Her family described her as “funny, kind and caring and loved by all”.
Her brother Jake called her the “best sister I could’ve ever asked for”, adding: “Hopefully she’s in heaven somewhere better.”
Her wider family described Demi as a “beloved” daughter, granddaughter, sister, cousin and niece.
“Demi loved her friends, and she was loved by all,” they added.