User blog comment:Mr Bio Shock/Attempting to Understand Infinite's Ending... (Spoilers, of course)/@comment-4920092-20130404205555

The reason for the tears is because Comstock funded Lutece's device that let her access other universes. Because Elizabeth(s) drowned Booker at some kind of convergance as he became Comstock, the tears never happened in any of the universes - they are all self-contained again. The reason there can still be a Booker and Anna is because in an infinite number of universes, EVERY choice happens. Therefore there is at least one Booker (probably many more) who never attempted to have a baptism at all, so he wasn't there to be drowned.