What to do with bad neighbors?

My fiance and I moved into a 2 family house 9 months ago. We live upstairs and a young man lives downstairs. We never had any problems up until 2 months ago. The guy downstairs had his "ex-girlfriend" move in that had just gotten out of jail so she had no where else to go. Before she moved in he also had another guy living their undercover that was not on the lease (but he kept a low profile and was no probelm). Also, we have a dog that we had to sign a contract for and pay a pet fee for every month. He has a huge dog and a cat living their without permission and now this girl. I dont care as long as they arent causing problems. But ever since he had this girl move in who isnt on the lease she has been telling my finace and I what she does and doesnt want us to do with our apartment. Telling us to keep our dog on a leash (he's a 10 lb. chihuahua) and not put our cigarte butts in front of OUR door. She mouths off comments to us every time we are outside. She has her dog out all day and we can't even use our yard. They smoke pot in their garage every night and have all their friends over every night drinking and standing around in the driveway till all hours of the night. We have never said anything to our land lord. We just moved to the area from hours away and dont know anyone here. But, this past weekend I had my sister and brother in law up to visit and I could tell the neigbors downstairs were pissed that I had visitors. They brought their two golden retreivers along and my bro in law was out on the lawn with his dog on a leash taking her to go poddy and someone downstairs told him to get off of the property before the dog downstairs bites his dog..I confronted the guy downstairs about EVERYTHING that has been going on since this girl moved in (bc it is her dog and cat) and he said that he would talk to her. Well, nothing happend and it continued. My finace callled the landlord and the landlord said that she is not on the lease there and that she is not allowed there and he doesnt want her living there. However, she wont leave and sits down on her porch and talks s*** all day long with her friends. We cant use the lawn and everytime we go outside she stares us down. My Fiance drives truck so I am here a lot alone and I hate it. They found out that we called the land lord and he came to my door and she came out and starting screaming at me out in the front yard at the top of her lungs. I just went in and said "i'm done" . My question after all this is what can I do? It's obvious the landlord isnt going to kick her out but she is not on the lease and I cant stand to live here with her anymore, but we are building a house and givinig our notice in 3 months and we are not going to move to another place for three months only....