Melissa Gilbert Grilled About 'Moments of Doubt' After Timothy Busfield's Arrest

Melissa Gilbert is defending husband Timothy Busfield ... telling "Good Morning America" that navigating his child sex abuse charges has been "hell."

In a preview for her upcoming interview, the morning show -- her first since her husband's been charged -- she said this has been the "most traumatizing experience of our lives."

In the teaser for the sit-down, host George Stephanopoulos asks Melissa point-blank if she thinks the parents and the alleged victims are "just making this all up" ... and she reacts by looking up and off to the side.

'GMA' dropped the promo during Thursday's broadcast, and George told his cohosts that Melissa "had a lot to say to defend Tim Busfield" in the "provocative" interview.

According to the daytime talk show, she insists in the full interview that her husband is "the last person in the world who would hurt a child," adding ... "For Tim, it's done. He's canceled ... even if he's exonerated, he will always be that guy."

She continued ... "Believe me, if I thought for a second that Tim Busfield hurt a child, he'd have a lot more to worry about than prison."

Busfield is being charged with two counts of criminal sexual contact of a minor under the age of 13 for allegedly abusing twin boys on the set of "The Cleaning Lady."

This is hardly the first time Melissa has come to her husband's defense over the charges ... she previously wrote a letter to the judge in his case, saying Busfield has "the strongest moral compass of any human I have ever known."