Tennant shared space issues

[Elizabeth A Johnson]

I live on the first floor apartment with my three children just the four of us. We have had several tenants move in and out upstairs and have had a wide range of issues. Nothing like this! There was a couple up stairs with a little girl, the wife moved out, and the husband moved in his parents to help with his daughter.(daughter isnt wifes kid) since they have moved in they have been extremely disrespectful cursing and screaming at my children for no reason grandmother has pulled everything out of the house and pressure washed it even electronics(so insane o know) and left it out there for almost a week. It looked like a full house was outback. I called and complained to the landlord and talked to the husband after noticing heavy Furniture items for stacked all over my glass table. Eventually the items slowly got put away however my backyard is now a toy junk yard, anything and everything found on the side of the road is in my backyard. They had a dog which they could not care for and left outside tied up all day kids would feed it and give it water thankfully I convinced him to find a dog a home. However the grandmother insisted that the crap outside was my dogs and I needed to pick it up instead of talking to me she spent a little girl over to have her tell me to "clean my dog s*** up". The little girl with the sweetest little thing and turned into a trash mouth. After I told her "honey it's not your problem don't worry about it talk to your dad about it" I thought it was all taken care of. I come home to a pile of fossilized s*** was on my doorstep. Now my dog is older and she literally poops right by my door and comes in we always pick it up. The back yard was our special place and i dont even feel comfortable out there now. The kittle girl and my son are friends amd i cant even let they play anymore because the grand mother curses at him and accuses of him of stupid stuff. They use my stuff have broken my table and trashed my fire pit. We each have a space for a washer and dryer in a shared basement/ storage area. They have filled the basement with junk and use my washer and dryer and throw my laundry on the floor! And they have there own units! Thay made me finally snap and yell at them... I already had to buy a new set because i was nice and let the last tennant use it and they over filled and broke it, and i wasnt even upset with them....Its just sad. Now the little girls father is a sweetheart and i know he is trying but his parents are just complete trash and have no respect for anyone and act like they run the place. Im am trying to avoid a huge confrontation and just talk to the dad who is the only one on the lease... Ive contacted my landlord she did call him and tell him to get it together. It just seems to make the grandmother more nasty and vulger and make more problems. 

help!!! What do I do???? How do I handle this??!??!