The burns on her face were so bad, doctors said, that they had to cut all the skin away. They employed a process known as excision, in which all the burned skin is removed and raw muscle and tissue are left behind. Then, a layer of cadaver skin is added to the open wounds, tricking the body into thinking it is new skin.
"It actually starts to heal a little bit. It allows the body to retain some of the moisture that it otherwise would be just overwhelmingly losing," Lettieri said.
Eventually, they used her own skin -- the few parts that weren't burned, including her scalp, inner arm and back -- to replace the cadaver skin and graft it on to the wounds. In other areas, they used cultured skin grown in a lab in Boston.
The lab would "send us a little rectangle, about 60, 70 square centimeters, at about $2,000 a sheet," Caruso said. Doctors used some 150 sheets on Stephanie.
As the patchwork of skin healed, it created thick, tender red scars that made movement painful. But the most excruciating part of Stephanie's awakening was yet to come.
At the time of the crash, all of Stephanie's children were under the age of 7. For four months, they had lived with family and Stephanie had missed the things she loved most as a mother -- birthdays, the first day of school and Halloween.
Their reunion was bittersweet.
The first to walk into the hospital room was Jane, her younger daughter. The girl was speechless when she saw her mother.
"I was like, 'Hi Jane.' And then I just will never forget her look that she gave me...And then she put her head down. She wouldn't look at me for the rest of the time. I wanted to die," Stephanie remembered. "It was awful to not have your own daughter not want to look at you just felt very, word, words just don't even describe that feeling."
Stephanie's older daughter, Claire, would only talk to her mother through a curtain.
There was more heartbreak to come; while Stephanie's older son, Oliver, greeted her calmly, her youngest child -- Nicholas, who was just 18 months-old at the time of the crash -- didn't know her. Stephanie's sister Lucy Beesley had been caring for Nicholas and he now called her "mom."
Nicholas, Stephanie said, would cry for his mom.
"I was like, 'That's me! You know, but I can't touch you, because my body hurts,'" she remembered. "It was awful."
Stephanie said the rejection by her own children and the limitations imposed by her injuries were almost too much to bear. She said she couldn't do all those little things that mattered so much.
"Just combing my daughter's hair, putting a little bow in her hair, or building blocks with my son, just simple things that mothers take for granted every single day... And I couldn't do it," she said. "So once those little things were taken away, it felt like my life was gone."
Stephanie's family pushed her to fight, just as she had fought for her life in the hospital. And her blog fans lent their support too, in jaw-dropping numbers: thousands of mommy bloggers, Stephanie's family said, spread word about the crash and donations poured in from around the globe. Stephanie's fans held garage sales, balloon launches and even benefit concerts. Support poured in from around the globe, including China and Australia. In all, a startling $250,000 was raised to help the family.
That outpouring notwithstanding, it was advice from Stephanie's father, she said, that finally helped her turn a corner.
"He was telling me, you know, 'This is just this in your recovery. You know, you won't be walking like this forever. And your face is going to get better...And look at this beautiful family you created. You can't just give up on them. And you're a mother, that's your job, that's what you want to do. And do it.'"
And she did, winning back her children in the process. By her third visit to the hospital, her daughter Claire was ready to talk without the curtain.
"She said, mom, I lost my tooth. I said, come show it to me," Stephanie remembered. "You know, so she finally came in with the tooth in her hand, and you know, looked at me, and we smiled, and we laughed like we used to."
Read Stephanie Nielson's blog, the Nie Nie Dialogues, and learn more about her long road to recovery on "20/20" Friday at 10 p.m. ET.