It sounds like you're expressing a sentiment of difficulty or discomfort in communicating something specific to your wife, even though you feel it's exclusive or particular to your situation.
The protagonist finds himself in an "impossible" situation where he has impregnated his mother-in-law. The phrase "even if my mouth is torn" (or "even if my mouth is ripped") is a Japanese idiom signifying a secret so grave that one must never speak of it, regardless of the consequences or pressure. Production and Cast Details