Sundahl, 44, was a pilot and had been working for several months as a private contractor ferrying officials across Afghanistan, reported Daily Mirror.
His devastated brother Karl said, "It's heartbreaking - John went there to try to repair the country. He was trying to help people, he would often say that the country was in chaos."
Spears, 33, dated Sundahl in 2007 after they met at an Alcoholics Anonymous meeting and she has credited him many a times with helping her beat her drink problems.