The suffering of children

About a month ago I bumped into a friend's husband on the street. His father had recently been hospitalized and I inquired about his health. We began to talk and he related to me that his sister had lost a child about a decade ago. She was inconsolable. Speaking to rabbis, psychiatrists, and friends couldn't help alleviate her pain. Then she read a book where she found answers that helped her deal with her situation. She read about souls being gilgulim that were sent down to the world to rectify a mistake made in a past life.
I recalled the incident when reading a devar Torah on this week's parsha on Revach.net.

People wonder, says the Ben ish Chai, how a child so innocent and pure can be stricken with severe handicaps R"L. What did these little children ever do wrong to deserve such a difficult future? Have they ever sinned? However he says, intelligent people understand that these children are gilgulim from previous lifetimes who have come correct their past errors. They pleaded with Hashem to curtail their power to sin once again. They are the ones who requested the impairment so that they cannot make the same mistakes again in this lifetime. Then at the end of their stay on earth they finally release their excess baggage and are free to go to the place in Shamayim they rightfully deserve.
This is hinted in the Pasuk, "V'Chi Yakeh Ish Es Ein Avdo O Es Ein Amaso V'Shichasa Lachofshi Yishalchenu", If a man strikes the eye of his slave, or the eye of his female slave, and destroys it, he shall set him free (Mishpatim 21:26). The man here, says the Ben ish Chai, is Hashem. If He strikes someone's eye and sends him to the world blind, guaranteeing he will never sin with his eyes, then when it is all over he will finally be set free.
Similarly, says the Ben iSh Chai, the next pasuk says, "V'Im Shain Avdo O Shain Amaso Yapil". Shain here can mean Shanim or years. If Hashem cuts down a young child in his youth, having his many years fall by the wayside, you must know that "Lachofshi Yishalchenu", Hashem sent him away for his own good.
http://www.revach.net/avodah/avodah/Parshas-Mishpatim-Ben-Ish-Chai-Why-The-Innocent-Children-Suffer/4375