HOUSTON — America has given much to Shaheen Khan. It has taken something, too. Three years ago, she was a nursery school teacher here, a meek woman with a melodic voice who charmed the children with tales from her native Pakistan. Today, Mrs. Khan shares a room in a dreary nursing home on the fringes of Houston, paralyzed from midchest down and tormented by a fateful choice to try to remake her life. Mired in debt and strained by a sometimes difficult marriage, Mrs. Khan signed up in 2004 with the military contracting giant KBR to do laundry for American forces in Iraq, a job that promised to triple the $16,000 a year she was earning at the school. She was assigned to work in the Green Zone in Baghdad, and she convinced herself that she would be safe. Five weeks after arriving in Iraq, she was speeding down a Baghdad highway in a Chevy Tahoe when the driver swerved to avoid a box he feared was a bomb. The vehicle rolled five times, leaving Mrs. Khan unconscious, suspended from her seat belt with a crushed spinal cord. Doctors have told her she will not walk […]