The mother of Libby Squire says she has lost "one of the most precious things" after her daughter's body was pulled from the Humber estuary.
The 21-year-old student was found on Wednesday, seven weeks after disappearing on 1 February.
Her death is being treated as a "potential homicide" and a man remains under investigation.
Lisa Squire posted on Facebook she was "so sorry she could not keep her safe" on the night her daughter vanished.
She wrote: "My baby girl is gone. Gone forever. No more birthdays with us. No more Christmas Days with us. No more family time all together.
"No family should have to endure that."
Mrs Squire, from High Wycombe, Buckinghamshire, said she was "broken" for all the people who knew and loved her daughter.
The "worst point" was having to tell her daughter's boyfriend Connor: "I am so sorry the girl you love the most in the world has gone".
"I cannot thank you enough my darling Pie for making me a mummy. For choosing me to be your mummy. It's an honour, a privilege and a joy," she wrote.
"I kept you safe for as long as I could and I am so sorry I could not keep you safe on that night. I'm sorry. I'm so so sorry.
"I love you my beautiful girl with all my being and I always will."
Miss Squire disappeared after a night out in Hull. Police believe she got a taxi from the Welly Club to her home in Wellesley Avenue at about 23:30 on 31 January.
She was spotted 10 minutes later on CCTV near a bench on Beverley Road, where it is thought a motorist stopped to offer her help.
Her body was recovered at around 15:30 GMT on Wednesday close to Spurn Point, near Grimsby Docks.
Detectives have said she could have been killed but "would not be releasing results of a post-mortem examination for investigative reasons".
An inquest is due to open and adjourn on Monday.