Saying that a gay person is allowed to marry someone from the opposite sex is the wrose argument I've ver heard. It's like saying the Soviet Union was a democracy b/c everyone had the same right to vote for the Communists. Crawl back into your hole and fetch better arguments.
Same sex divorce is on the questions that must be ask about when discussing same sex marriage. Marriage creates a contractual relationship and there is every reason to believe that these, lke different sex relationships, will end.
so make it exactly the same way heterosexual divorce is handled. problem solved.