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(CNN) - Boston Marathon bombing survivor Jeff Bauman's haunting, ashen face became an iconic image of the terror unleashed that day last April. He lost both legs in the attack.
Bauman's new book, "Stronger," begins with a chilling description:
"I know exactly when my life changed: when I looked into the face of Tamerlan Tsarnaev. It was 2:48pm on April 15, 2013-one minute before the most high-profile terrorist event on United States soil since September 11-and he was standing right beside me."
"It started out as a really cool day in April," Bauman says.
Bauman was at the finish line with a couple friends, waiting to cheer on his then-girlfriend (now fiancée) who was running the race. He spotted a young man with a bag who looked completely out of place. Bauman looked down, the man was gone, and then saw an abandoned bag.
"Next thing I know I was on the ground. I heard a pop and saw a flash," Bauman said in an interview with CNN's "The Lead with Jake Tapper."
After Bauman woke up in the hospital, he was able to give a description of who he saw. To this day, police give Bauman tremendous credit for helping the investigation.
"It was tough at first, I woke up and was instantly surrounded by people," said Bauman.
Alongside loved ones, the police and FBI investigators were also stationed outside Bauman's hospital room.
They came in, and Bauman still had breathing tubes in. He was eventually able to talk, telling investigators what he saw. Investigators showed him pictures and Bauman worked with a sketch artist to identify Tsarnaev.
Bauman does not like looking at the photo of him being rushed away from the scene, his legs gone, his face drained of color.
But he likes looking at the faces of the people who helped him that day, including the man in the cowboy hat – Carlos Arredond. Arredond lost both his sons, one in the war in Iraq, and one later to suicide.
He was handing out flags for the veterans on the day of the bombing, and was across the street from Bauman when the terror began.
“He’s a great person,” said Bauman. “He’s got a great heart, and he’s very, very genuine and nice. Our relationship is great.”
In his book, Bauman is candid about the difficulty of adjusting to life after the attack. Using his prosthetic legs is challenging. He also lost some of his hearing because he was so close to the bombs when they went off.
But he had a goal: to be able to walk by this year’s Boston marathon.
“I’m pretty close. I walk with crutches now,” said Bauman. “The most difficult part is getting your strength up.”
His legs are also extremely sensitive.
“My nerves are always shooting off, and it’s very different from the past 27 years of my life to now,” said Bauman.
There are also mental hurdles to putting on prosthetics day in and day out.
“It’s an unnatural thing to put on these heavy prosthetics and get moving with them,” said Bauman. “It’s kind of a struggle when I wake up in the morning to want to put them on, because my legs feel good, and then I put them on and they get tired.”
But Bauman said it “gets better every day.”
“I can’t wait to see where I am a year from now,” said Bauman. “I’m going to be doing a lot better.”
During his recovery, knowing the struggles ahead, Bauman told his girlfriend, Erin Hurley, she didn't have to stay.
"He said if you want to be here that's great, but you don't have to stay with me," Hurley says.
But Hurley says that was never an option for her.
The couple has had their ups and downs. In the book, Bauman describes a fight in a car where he becomes so angry, he bangs the dashboard and breaks the radio.
“In any stressful situation, no matter who it is, you’re going to have conflicts that come up, whether it’s your partner, or your sister, or your mom,” said Hurley.
"We had to learn a lot about each other in a very short period of time," said Hurley. But the struggle "has a silver lining to it because now, you know, we both know we're going to be there for each other, no matter what."
Bauman details in the book the incredible source of strength Hurley was during his rehabilitation, saying he would not be where he is today without her.
They are now engaged and expecting their first child.
Watch or full interview with Jeff Bauman and Erin Hurley in the videos above and below.