oh dear. You aren't stuck in a lease, really.
If you have been documenting your efforts to get the roof repaired, (not through phone calls, with actual copies of letters you have sent), and snapping pictures every time it rains, you can break your lease with confidence that you'll win in the ensuing court battle.
The judge will take one look at your evidence, and void the contract. And they'll be forced to return your security deposit.
So don't suffer, you aren't as trapped as you think. Another thing, if you haven't already, don't take your landlords word for anything until you look up your states landlord and tenant laws and verify that what he is saying is true. He will try to convince you that you cannot break your lease.. of course you can. And you can have a judge decide if you should have stayed or not (his answer will be NOT, if you followed the steps above.)