How would you deal with a landlord who broke all her promises?

My wife, 4 year old son and I moved into a 3 BR apt on Long Island, NY in May. Before we moved in, we had at least 5 conversations with our soon-to-be landlord about the reasons we were moving. We told her that the 2 main reasons we were moving was because:1. The other place was too noisy and 2. We wanted a place with a yard for our son to play in.

Before we moved in our landlord pointed out they were still doing some work on the downstairs 1 BR apt, so there might be noise on weekends, which we said was fine as long as they were done and gone by 7:30 PM.

1. We asked and reiterated 5 times that we do not want to live above someone with a kid of any age. We were promised over and over that she would only rent to a single person with no kids and no pets.

After 7 months of working on an apartment that was only supposed to be 1-2 months to work on, she finally rented out the space to a Single Mother with a 20 month old girl, and her boyfriend. The place is extremely noisy until at least midnight. The little girl runs around screaming, they slam doors, cabinets, drawers, etc... and the boyfriend screams at the top of his lungs. This was the biggest and most important promise made to us

2. They said the work on the downstairs apt and around the house would be done within 1-2 months. It is now going on 7 months. Also, even though we were promised that no workers would be there past 7:30, that has changed. They were even here hammering and banging away on Thanksgiving day for 7 hours!

We signed a 3 year lease, but we dont want to move. Our landlord pretty much has told us she doesnt care about the promises she made. It seems like she told us that just to get us in the door. Unfortuantely, I am trusting and usually take people for their word.

We cannot afford to move, nor do we want to because we like the school district. We pay our rent on time every month (sometimes a day or 2 early). We are quiet, respectful, clean, etc....but now our landlord has made us feel like we are the bad guys.

A lawyer suggested I send a certified letter with my complaints, but I dont know what good that would do...it doesnt seem like she cares.

Any advice?