พี่สาวแสนสวย

Thai Translation
เธอเป็นพี่สาวของภรรยาผม และเธอยังเป็น...
Translation Notes:
Used "เธอ" (she) as the subject pronoun to maintain the personal tone
Translated "老婆" (wife) as "ภรรยา" which is the standard Thai term for wife
Used "พี่สาว" specifically indicating older sister, preserving the family relationship dynamic
Added "ของ" (possessive marker) to properly structure the Thai possessive form
Used "ผม" as the first-person pronoun, assuming a male narrator based on context
Maintained the ellipsis (...) to preserve the narrative suspense/unfinished thought
Used "และ" (and) as a conjunction to maintain the flow between clauses