Newtown victim's parents talk about meeting killer Adam Lanza's father

(CBS News) Vice President Biden and New York Mayor Michael Bloomberg are expected to meet with the families of Newtown school shooting victims on Thursday, over three months after the massacre took place in Connecticut.

Ahead of the meeting, CBS This Morning's Norah O'Donnell spoke with Robbie and Alissa Parker, the parents of six-year-old victim Emilie Parker.

They revealed that they recently met with the father of gunman Adam Lanza as part of their search for understanding and grieving process.

The meeting "was kind of my doing," Alissa Parker explained. "I guess the reason why I felt strongly that I needed to tell [Peter Lanza] something. And I needed to get that out of my system. I felt very motivated to do it and ... I felt really good about it, I prayed about it, and it was something that I needed to do.

Robbie added their family has experienced "a little bit of everything," as they've dealt with the scope of the tragedy over the past three months.

"You know, you went from the absolute worst experience that you could ever imagine to have to go through as a parent ... and being overwhelmed with that sense of grief and loss to, on the other end of the spectrum, you're being completely overwhelmed with outpouring of love and support from so many people and everything that kinda falls in between," he said.

The Parkers addressed the recent news that Newtown investigators determined that Adam Lanza kept a spreadsheet methodically detailing the death toll of other mass shooters, types of weaponry, and plotted how he would add to the death tolls.

"Any information ... that you gain in this experience is just that. It's information," Robbie said. "And then you have to choose how you're gonna handle it. And so for us, we've decided that what works best for us is you receive a bit of information, you process it, you feel the emotion that comes along with it, and then you have to let it go."

Alissa added, "It's just like another piece to the puzzle. And it always brings with it a period of, you know, sorrow, pain, and you deal with it and you just move on. The outcome is still the same, regardless if it was planned, not planned. But it doesn't change anything. It doesn't change that our child's gone."