My husband keeps threatening to divorce me every time we argue. What should I do?

Repeated threats of divorce are a form of emotional pressure that does not fit Islamic character, and must be dealt with seriously.
Talaq is not a tool for frightening; Allah warns against making His verses a jest (2:231). Persistent threats can count as emotional abuse under Malaysian law. At a calm moment, tell him the effect the threats have on you, and ask him to promise not to use them again. If words of talaq have actually been uttered, do not decide for yourself whether it has taken effect — refer to the Syariah Court or the religious affairs office for confirmation, as it depends on the words used and the intention. Get counselling, and see Talaq & divorce.