Mother-of-three Debbie Griggs disappeared without a trace on May 5, 1999 and has not been seen since.
At the time of her disappearance from the family home in Deal, Kent, she was pregnant with the couple's fourth child.
Ms Grigg's father has said her mother "died of a broken heart".
Now Andrew Griggs, 57, has been jailed for life with a minimum term of 20 years.
He was found guilty following a trial at Canterbury Crown Court on Monday and sentenced at the same court on Wednesday.
Mr Justice Robin Spencer, sentencing Griggs, said: "Her body has never been found, only you know how you killed her and where you disposed of her body.
"You told lie after lie in the witness box, just as you did at the time of Debbie's disappearance.
"In murdering your wife you destroyed the life of that unborn child as well.
"I strongly suspect that you dumped her body at sea.
"You knew that stretch of coast like the back of your hand. It would not have been difficult to weigh her body down so that it sank."
The judge said the length of time Ms Grigg's body has been concealed for - 20 years - and the fact that Griggs has still not revealed its location, was an aggravating factor in sentencing.
"You robbed the mother of her children and her family of the very thing you have enjoyed over those 20 years.
Mr Justice Spencer paid tribute to Ms Griggs, of whom he said "caring was her very nature".
He said he had "no doubt whatsoever" that Andrew Griggs had been in a "full sexual relationship" with a teenage girl in the months before his wife disappeared.
Mr Justice Spencer told the court that he had to sentence Griggs in line with the law that was in place at the time of the killing.
Taking everything into account, he jailed Griggs for life with a minimum term of 20 years.
Detective Chief Inspector Kaye Braybrooke, of Kent Police, said: "We are happy that the family have finally got some sort of closure and hopefully they can now have the opportunity to continue with their grief.
"We will continue to look for Debbie when there is evidence and information that comes in.
"I would like to appeal to Andrew Griggs to say that it is not too late. He can still speak up and tell us where she is."