Pray, dear brother. Pray, pray, pray.
I am learning to fight every battle on my knees. It's the greatest secret weapon I have. If you abandon yourself and take this matter to God, he'll rectify it. Can I give you some inspiring examples of how God works on behalf of his saints?
I once had an automotive specialist work a car I owned. He jacked it up pretty bad; he put the belts on backwards and installed a water pump wrong. As result, I ended up blowing out some pistons and ruining the entire engine. I wrote him a letter, and the company denied culpability. The owner even cussed at my wife over the phone! I was enraged. They told me to sue them, they were sure they would win! Well, I was ready to get them served, when I got hold of my bearings and took it to God in prayer. The Holy Spirit told me to drop the case and not do anything! Well, I obeyed. The next time I went by the place (about a week later), the shop was totally closed down. The signs were all gone, all the cars were gone. God took that entire garage away, and I received a brand new car shortly after.
Another story involved my pastor who had moved into a new home where the next door neighbor's dog wouldn't stop barking. He would go all night long. Finally, it just got to be too much. He was getting out of bed to go knock on their door, when he decided to pray first instead. He got down on his knees beside the bed. He said that he had hardly started his prayer, when the dog suddenly shut up. It was so sudden and drastic, he seriously thought God had killed the dog! To this day, he says that after a certain time, the dog never barks.
If you really want some inspiration on the efficacy of prayer, read up on a man of God named George Muller. It'll boost your faith! However odious this family is, God has a solution. You should allow God to handle them. Maybe he put them there to teach you patience; maybe he put them there to drive you to your knees. In any case, if you pray, something will happen. My brother-in-law is a strong man of prayer; I've seen him systematically pray ungodly boys out of his daughter's life. I've seen a kid go to jail, another one just disappear, another move to a different school. One after the other. You ask him about what happens to all the boys, and he just says, "Oh, I've prayed them out. They're not Christians."
Bro. Paul