I am renting a condo is Florida and opened some mail by mistake to learn that the owners are behind on their condo fees and being threatened with Foreclosure. What happens to my one year lease if that happens? And how can I be sure I will ever see my $1600 security deposit back?

First I am not sure that a condo owner can actually be foreclosed just for condo fees, they can put a lien on the property if they are not paid,

But you really have no way to ever be sure you will ever see a deposit back from anyone. Your recourse will be to sue them in civil court for the money if they don't pay it.

First of course there will be months of court for them to place a lien and then go though foreclosure procedure depending on at what point they are in the process.

But if a property is sold at a foreclosure, the lease terminates and is void, so who ever buys it at foreclosure has no obligation to honor the lease.

If it does foreclose, the person is suppose to pay your deposit back, but be realistic, if they lose a condo for fees, they are broke anyway and have no money to pay you, you can of course sue them for the money