Arguement with landlord over new tenant's dog poop.

Ok so I'm really curious to get you guys opinion on this issue. I currently live in a 2 story duplex and we are on the 1st floor. This is currently our 6th year here. For the past 5 years we have been wonderful tenants that take very good care of the property and have barely even so much as called my landlord for anything that wasn't an emergency. We do pretty much everything ourselves not to mention this man has gotten his rent EVERY SINGLE YEAR for 6 years straight in a lump sum. We always like to pay an entire year in advance so that is what we do every year. New tenants moved upstairs 3 weeks ago and they have a dog. It is 3 adult women up there and a child. The women are very rude and if you say hello will totally ignore you. Ok so me and my husband have not bothered to have any contact at all with these people we keep to ourselves because of their ignorance. In front of our living room windows is a small front yard with a little garden underneath my window that I have been maintaining for the past 6 years. These people insist on walking their dog in the front yard letting it poop all over the front yard including directly under my living room front windows. There is a huge side yard that belongs to them. I wouldn't care if they walked their dog on their yard as we dont ever go in their side yard. We have the backyard and small yard out front because we pay much more for it. They never pick up the poop they just let the dog poop and then go back inside. Now when I open my front windows all you smell is shit. Me and my husband and my 2 small children have stepped in the poop walking through the front yard. Me and my husband were cleaning it up at first but we got fed up and stopped. I got so fed up that I put a small "please curb your dog " sign in my front window where they let the dog poop daily. Instead of being responsible they completely ignore the sign and let it poop there anyway. About 2 weeks ago I stepped in their dog's shit AGAIN. I grabbed a plastic bag cleaned it up tied the bag up and stuck it on their side of the front porch that we both share since there was no trash cans out there at the time. Well 3 days ago I get an angry call from my landlord stating that he wants me and my husband to stop harassing the new tenants. I said excuse me harassing? We haven't had any contact with these people AT ALL so what are you talking about? He goes "they claim you are harassing them over dog poop and that you tossed a bag of their dogs poop on the porch and put up a sign up in your window that they know was directed towards them". I tried explaining calmly what they were doing with their dog at my front window and he yells "its not your problem you dont own the property " I said well it is my problem because I can't open my living room windows without smelling shit". This man doesn't want to hear anything I have to say. Yelling at me to leave them alone and let their dog be. My husband then gets on the phone and he starts yelling the same thing at him. I even tried to be the peacekeeper and asked if we could all have a meeting in person to discuss this in a civil adult manner because we dont want any problems and his response was " absolutely not there is nothing to discuss and I have nothing to say to you people just leave the new tenants alone". We are completely blown away by this entire situation not to mention sick over it. We never had a bad relationship with my landlord in all these years we have lived here both me and my husband never had any problems with him. We are now miserable and beyond stressed out. My husband had a stroke a year ago so neither of us need this shit. Both our blood pressure is now through the roof. I feel extremely betrayed also very angry and hurt. At the time when my landlord called me and started yelling at me about the new tenants accusations there was guests here visiting that were sitting right here with me and witnessed the entire argument and got extremely upset and are now infuriated with my landlord for treating me and my husband like this. I don't know what to do there is no reasoning with this man and the people upstairs have us infuriated! We had no intentions of moving but now we feel like we have to. We can't live in a place with such a disrespectful landlord and tenants. We feel like they are trying to push us out. If anyone else had a similar experience what did you do?