A marriage may be annulled by an action in the circuit court to obtain a decree of nullity if, at the time of the marriage, the consent of either party was obtained by fraud, unless such party afterwards, with full knowledge of the facts constituting the fraud, freely cohabitated with the other as husband or wife. An action to obtain a decree of nullity of marriage for causes mentioned in this section must be commenced by the party injured, within four years after the discovery of the facts constituting the fraud.
SDCL 25-3-6