Renter in potential rental hell, advice requested.

I've had some slum lords before. You can do a constructive eviction in Indiana. Basically you can claim the property is uninhabitable because of the door situation. Then, as long as you have fulfilled your end of the lease thus far, i.e. You get your rent paid up and don't owe him anything, you move out, then sue him for every penny you've paid him. As far as the late fees go, I won in court against a landlord because my awesome pro Bono lawyer friend found some court case where you can't charge late fees unless you can prove that you as the landlord have incurred at least that amount in damages as a result of your tenant paying their rent late. Or something like that. I'm a biologist. Any lawyers out there? Help me out. I stopped paying rent cause of some roaches and when I moved I sued. But because I was behind, I got screwed. But i won every late fee id ever paid the s.o.b. So we broke even. Get caught up, move out, sue. But be patient. God speed.