(CNN) -- On February 12, 2009, Christopher Savoie received an e-mail from his ex-wife that he had feared would come.
Christopher Savoie is in jail in Japan after trying to get back his son, Isaac, and daughter, Rebecca.
About a month after their bitter divorce, in which Noriko Savoie promised as part of the agreement she wouldn't return to Japan with their children to live, she threatened to do just that.
"It's very difficult to watch kids becoming American and losing Japanese identity,'' Noriko Savoie wrote her ex-husband in the e-mail, according to Tennessee court documents. "I am at the edge of the cliff. I cannot hold it anymore if you keep bothering me.''
Now she is in Japan with the children. Christopher Savoie sits in a Japanese jail accused of trying to kidnap them.
He practically predicted it would end this way.
The couple, citizens of the United States and Japan, were married for 14 years and lived in Japan. But they came to the United States with 8-year-old Isaac and 6-year-old Rebecca. They divorced in January 2009 after Christopher Savoie was unfaithful. Noriko Savoie was given custody of the children and agreed to remain in the United States.
During the divorce, Christopher Savoie was concerned that his ex-wife would move to Japan with the children. After receiving the threatening e-mail, he went to court to try to prevent that.
He pleaded with a judge in March to stop Noriko Savoie from being able to travel to Japan for summer vacation.
He knew if she took the children to Japan to live the deck would be stacked against him. Japanese law would recognize Noriko Savoie as the primary custodian and he might never see his children again.
Noriko Savoie told a judge the words in her e-mail were in the heat of the moment; she was angry that her ex-husband had just married the woman who caused their marriage to end.
"I was very, very -- at the peak of my frustration ..." Noriko Savoie told a judge, according to court transcripts. "He actually married three days before that e-mail. He remarried the person -- a woman whom he was having affair [with], so I was very depressed and -- but also angry."
Noriko Savoie was asked repeatedly in court if she would try to take the children and flee to Japan. Her answer was always no.
"I have never thought about taking children away from their father, never," she told the judge.
Christopher Savoie didn't believe her.
Their divorce had been rocky, both of them said. The court documents reveal bitter fights and mediations during the divorce. The two accused each other of sending harassing e-mails. They also fought over sending the kids to baseball, Scouts and other activities. Noriko Savoie accused him of not giving her enough money to take English language lessons or go to school so she could get a job. He accused her of not trying hard enough to enroll or find a place to live. Dad paid ex-wife $800K in divorce »
Despite those issues, Christopher Savoie said his only concern was making sure he wouldn't be separated from his children.
He knew trying to get the kids back would be "a futile effort" if Noriko Savoie did flee with the children, according to court documents.
He laid out in court a scenario similar to what he is facing.
"If she were to go to Japan with the children and with primary custodial rights, there's pretty much no doubt that I would have a very difficult time enforcing my rights to visitation should Noriko decide not to let the children see me," he said.
He said he'd have a hard time paying expensive legal fees because most of his money was tied up in his house, car and 401(k) after he gave Noriko Savoie more than $700,000 as part of the divorce settlement. With that money, he feared she'd be able to move and hide the children from him.
When appointed parental coordinators asked her if she planned to take the children to Japan, she hesitated and simply answered "I think the kids will be happy if I'm happy." The judge asked Noriko Savoie rhetorically whether she would be willing to put up money, essentially a bond, to ensure she'd return from Japan. She agreed, but was never asked to do so.
Judge James G. Martin III warned Noriko Savoie she would lose her alimony, education funds and other money if she fled with the children, before ruling that he believed she wouldn't abscond with them and allowed her to travel to Japan.
Noriko Savoie followed the court's rules and took the children on vacation and returned during the required time to the United States. But days later, she took the children back to Japan.
The court in the United States granted Christopher Savoie full custody after Noriko Savoie fled the country. But that court order means nothing in Japan, where courts generally favor mothers in custody disputes.
The couple is also still considered married in Japan, because they never divorced there, Japanese police said Wednesday. And, police said, the children are Japanese and have Japanese passports.
A 1980 Hague Convention standardized laws on international child abduction, but Japan is not a party to that agreement.
Christopher Savoie knew all this when he decided this week to go to Japan to get his children back.
He took the children as Noriko Savoie walked them to school Monday in Yanagawa, a rural town in southern Japan. He headed for the nearest U.S. consulate, in the city of Fukuoka on the Southern island of Kyushu, to try to obtain passports for the children, screaming at the guards to let him in the compound. He was steps away from the front gate but still standing on Japanese soil when he was arrested.
Christopher Savoie, who will be in jail for the next 10 days while Japanese officials sort out the situation, told CNN's Kyung Lah that he was scared and just wanted to see his children.
"I love you, Isaac, Rebecca," he said. "Your daddy loves you forever. I'll be patient and strong until the day comes that I can see you both again. I am very sorry that I can't be with you."
Though he had warned everyone this was going to happen, this time he could speak in certainties.
He said that though he knows it might be a tough battle, it's one he will continue to vocalize.
"I want Americans to know what's happening to me," Christopher Savoie said in Japanese. "I didn't do anything wrong."