Ability to break lease agreement

We have had a ton of issues with our landlord not taking care of our property. We live in a 3 bedroom front house, and have two 1 bedroom units on the property. A few days after we leased the front house, our landlord rented out the available 1 bedroom unit in the back (the other one already had/has a tenant). These new tenants were bringing in 3 large dogs. The landlord agreed that he would not allow them to leave dog feces on the property, and wouldnt allow them to have their dogs run rampant. As you can imagine I am saying all of this because from day one, we have had a constant problem with both of those. I have contacted my landlord several times, but it has fallen on deaf ears. I have emailed digital pictures of the dog feces, and he never responds.

Next-when we moved in there were several things we needed fixed. Most importantly is the heater. In every email I have mentioned that these things need to be fixed. Again, he has never responded. On month two I spoke to my landlord over the phone, and he agreed to come and do a walkthrough so we could point out the things that needed to be fixed. He never bothered to show up, and called about 5 days after the fact with some lame excuse.

Obviously this situation is not something Im willing to put up with any more. With my last rent check (November 1st) I sent a letter again explaining our problems with the back tenants, and the things that needed to be fixed including the heater. 10 days later, no response. And the rent check has cleared.

We signed our lease agreement in August, and it was for 9 months. We want to leave now. Especially since the cold is setting in, and its going to be absurd for us to use electric heaters to heat the place.

I have copies of every email sent, as well as the letter I sent.

Can we break this lease agreement? Also can we expect to get our deposit back?