Sex Triangle: Where Is the Missing Teacher?

A deadly love triangle that rocked a quiet Tennessee community has gotten more complicated.

It started with a relationship between 30-year-old then student teacher Erin McLean and 18-year-old student Sean Powell. Powell is dead, Erin's husband, Eric, is accused of fatally shooting him and now faces second degree murder charges.

Erin is now missing, along with the couple's two boys, after she was accused of inappropriate conduct with yet another teenager.

Their whereabouts are a mystery that plagues Eric, who despite being granted visitation rights while he awaits trial, does not know where his sons are.

"I can't sleep or eat. I talk to people about it all the time, and it's just driving me crazy," Eric told "Good Morning America" in an an exclusive interview.

Police say Erin moved with her two sons to Nashville, Tenn., after Powell, from West High School in Knoxville, Tenn., was killed.

In Nashville, officials say she used her maiden name, Erin Meyers, to get a job as a teacher at Pioneer Christian Academy, where she has since been accused of inappropriate conduct with a student.

"There was a lot of phone calls going to a particular student. She wasn't forthcoming in her answers and what was on her resume," said Jeff Darnell, headmaster of Pioneer Christian Academy.

Eric's lawyer, Bruce Poston, says the second set of accusations is verifiable.

"I went out to Nashville. I met with the boy himself. She went after a 17-year-old boy," Poston told "GMA," adding that in one night, she'd made 22 phone calls to the boy from a Nashville hotel.

"Their godmother said the hotel they were in was a cesspool of whiskey bottles and trash," Eric said.

Erin's lawyer, Gary Blackburn, argues the focus should not be on her, but on her estranged husband, Eric, because he is accused of murder.

"The choice of having an affair with an 18-year-old was a poor choice. It seems to me to pale in comparison with the choice to murder him," Blackburn said. "Why is the focus then on Erin and her misbehavior rather than on Eric, the man with the rifle?"

A Relationship Goes Terribly Wrong

On March 10, 2007, Erin made a frantic 911 call from her Knoxville home after Eric allegedly shot Powell. He'd allegedly found Powell and Erin together in the couple's house.

"He shot him with a shotgun. Please come, hurry, hurry," she cried to the operator.

Eric was arrested and is facing up to 25 years in prison for the murder of Powell. His trial is scheduled for January.

Blackburn, Erin's lawyer, says he has been in contact with her and says she and her sons are hiding in another state, but they are all safe.

"I think Erin has been very much in need of treatment and there has been a concentrated effort to destroy her," Blackburn said.