Saints tight end Foster Moreau was emotional after dropping a touchdown pass that could've sent his team into overtime on Thursday night ... admitting the play put him in "a dark place."
The 26-year-old, who beat cancer to return to the field this year, had a chance to help New Orleans tie its "Thursday Night Football" game against the Jaguars with just seconds remaining on the clock ... but the TD pass slipped right through his fingertips -- and the Saints went on to lose, 31-24.
Afterward, Moreau -- seemingly on the verge of tears -- called his effort on the play "unacceptable" and "pathetic.