Can I break my lease because of my neighbour’s harassment?

I have 2 kids one 7 year old old and the other 2 year old(son). we received too much harassment from our neighbour. we informed this to our landlord and kept him posted on every single thing. we also informed this to the local police. When the harassment was turned to some sort of threat(our neighbour left a note on our door informing that he is going to call DCF) we really got scared and informed the landlord that we would be vacating the place and gave him 30 days notice. he agreed but after 2 months when we asked him the last month rent and the security deposit that we paid he sent us a notice that they were used for the last 2 months rent and if the unit is not rented by 31st Dec we will have to keep paying the rent. He did repair of the house as soon we left and has not done any attempt of renting it. He didi not mention any of this to us before we left. We are ready to let go off the security deposit and the last month rent as a fees for our sanity but can he charge more than that?