Kim Mclaughlin made the moving tribute to Josh James-Stewart, 16, one of three teenagers who died when their car crashed into a wall on Monday night.
Police have launched an investigation into the accident on an unclassified road near the village of Tyninghame, near Dunbar, in East Lothian, which also claimed the lives of Jenna Barbour, 18, and 15-year-old David Armstrong.
The only survivor of the accident, Robbie Gemmell, 16, was rushed to Edinburgh Royal Infirmary and was said to be sitting up in bed in hospital yesterday after initially being admitted to the intensive care ward.
The three boys were all in their fifth year at Dunbar Grammar School, and Jenna had left the school in the summer.
Police said the car, a dark green Peugeot 206, had been on a straight stretch of road leading to Tyninghame beach when it ploughed into a brick buttress supporting a wall at the Tyninghame Estate at around 8:30pm.
Kim, 20, from Dunbar, East Lothian, where all the victims are thought to have lived, posted a series of moving Twitter tributes to Josh. She wrote: “My heart is broken into a thousand pieces. I will always love you forever.”
Kim, a nursing assistant, added: “I love you more than anything. Maybe if I fall asleep I’ll wake up and this will all have been a nightmare.
“I would give my life to have him back. So I’m going to try and sleep so at least come cuddle me. You know how much I hate being cold. Goodnight Josh I love you.
“Being awake hurts too much.”
David’s sister, Gemma Armstrong, posted on her Facebook page a picture of them together when they were children and wrote: “I miss you so much big bro and hope you are happy and I will always love you and you will always be in my mind xxx”
It has emerged that the crash could have claimed a fourth young life. Nathan McMaster, 19, said he was invited for a drive by the group on Monday.
Nathan said: “They called me on the night of the crash and told me they were going for a drive and that’s the last time I heard from them.
“The next morning I found out they were dead.”
On Tuesday night hundreds of mourners turned up to a vigil in memory of the three teenagers at the Hallhill Healthy Living Centre.
Dozens of flower bouquets have been left at the side of the road, known as Lime Tree Walk. A Dunbar RFC top has also been left in memory of the boys, who played for the local team.
Chic Brodie, SNP MSP for the South of Scotland, whose constituency includes the scene of the crash, said: “This is the worst of times for parents when they lose a young member of their family. It is a heartbreaking situation and all of our thoughts are with the families and friends.
“I know how it felt when I was told my son had been in a serious road accident in 1992, and my first reaction was to jump in my car and try to get to where the accident was.
“He survived, but I know the emotions that go through a parent’s heart.”