St. James said in his epistle that we should "pray for each other" and that "the prayer of a righteous man is powerful and effective" (James 5:16) This is what this forum is all about.
your friend's friend will be in my thoughts. it's tough helping someone turn away from suicide. often by that point, the individual's thinking is irrational and hard to argue with. but it is possible to escape saddness and move on in life. hope he or she make sit out of this darkness.