Rebecca Aylward's family speaks after verdict
Within minutes of Joshua Davies being found guilty of murdering Rebecca Aylward, her family described her death as a "senseless and barbaric act".
In a statement issued through police, the family said that their lives had "stopped" since her death, and they could "never" forgive Davies.
Local parish priest, Father John Meredith, said the community missed Rebecca "every day".
The Crown Prosecution Service said the murder was "planned and calculated".
After the verdict, police issued a statement from Rebecca Aylward's family, which said: "The pain and horror of losing Rebecca in such horrendous circumstances cannot be put into words.
"Since that Saturday in October 2010 our lives have stopped.
"Rebecca was killed in a senseless and barbaric act. She died at the hands of someone she loved and trusted.
"We will never forget what he did to her or forgive him for destroying our family.
"We would like to thank the prosecution team for their meticulous hard work."
Det Ch Insp John Penhale of South Wales Police said: "This was a tragic incident which brought shock and sadness to a close-knit community.
"Our thoughts today are with Rebecca's parents, relatives and friends who I hope have been given some closure as a result of the jury's decision.
"I would personally like to thank the community for their support during the investigation and to the prosecution witnesses who gave evidence at the trial."
Richard Killick, of the Crown Prosecution Service, said: "Today's verdict marks the conclusion of what has been a very sensitive and difficult case to investigate and prosecute.
"This was a planned and calculated attack on a defenceless 15-year-old girl, resulting in her tragic death.
"Only the defendant truly knows what motivated him to commit such an act - but what we do know is that Rebecca's family and friends continue to live with the awful consequences.
"We can only hope that today's verdict will, in some way, help them as they try to move forward with their lives."
Father John Meredith, school governor at Archbishop McGrath Catholic School, and parish priest for Our Lady and St Patrick's Catholic Church, Maesteg, said the death left the "entire community profoundly shocked and saddened".
He added: "Today will have been particularly difficult for her family, but we will always remember Rebecca as a friendly, well-liked and hard working young person with great potential.
"We miss her every day.
"The ways in which her family, friends, fellow pupils, teachers, governors, school staff and all who knew her, have supported and cared for each other during these last few months is a mark of our deep respect and love, both for Rebecca and for each other.
"We are, thank God, a very strong community, and will continue to support one another with compassion and love.
"Our thoughts and prayers continue to be with Rebecca, her family and all those who have been affected by these tragic events."