(a) Bigamy.— A married person is guilty of bigamy, a misdemeanor of the second degree, if he contracts or purports to contract another marriage, unless at the time of the subsequent marriage:

1. (1) the actor believes that the prior spouse is dead;
2. (2) the actor and the prior spouse have been living apart for two consecutive years throughout which the prior spouse was not known by the actor to be alive; or
3. (3) a court has entered a judgment purporting to terminate or annul any prior disqualifying marriage, and the actor does not know that judgment to be invalid.