Expressing shame in your native language is a problem everyone faces, but it becomes much easier when using a foreign language, especially for many small, difficult-to-utter matters in close relationships.

Native vocabulary carries a lot of emotional memories and cultural weight, so before describing something, you already feel the intense emotions wrapped inside, subconsciously imagining many "negative consequences."
Foreign vocabulary, on the other hand, is more like a "neutral symbol," which reduces activation of the amygdala and has a built-in "cognitive dissociation" function. This makes it easier to say words that were originally stuck in your throat.