I don't know anything about how legal matters work in Singapore. But in the USA, as a civilian, the best mode of action is to say nothing and hire a lawyer to speak for you. This video explains why.
However, in Singapore, if your govt does not recognize your inalienable right to remain silent in order to avoid unintentional self-incrimination, then this could be bad advice. It was meant for the USA.
Seek legal counsel. However, if the worst that could happen to you is a fine of less than $2,000 USD, then you may just want to throw yourself at the mercy of the court and plead insanity.