i want to file an annulment case on the grounds that my marriage is bigamous. question is "do i have to prove in the court that the 1st wife is still alive when our marriage took place in order for me to use the bigamous ground? is a valid marriage contract good enough to grant an annulment? it is very hard to prove that the 1st wife is still alive when we got married because even my husband does not know her whereabouts anymore.

Thank you