Before getting married, I bought a house that was closer to my husband's kids, 3 teenagers, 13-17.  The middle 15-year-old boy has always been disrespectful, not just of me, but of every adult I' have witnessed him interact with.  I ignored it but kept waiting for his father to correct him, which he did by saying "That’s enough", after he noticed me getting extremely upset.  

This boy has repeatedly been caught by his mother smoking pot with his cousins to give you some background.  A week after buying the house, he was here with the youngest girl and they were walking around looking at where their new rooms would be, when I told him the ground rules.  It was my house, and my rules applied.  I told him, that I did not care what his mother allowed.  Homework by him at once when he came in after school, no yelling, but mostly if I ever found out he had weed, or anything else illegal, his parents would not be my first call, but the police to remove him from the property.  I was not kidding.  No illegal drugs in or around my house.  

The next week he told his dad he did not want to go for the weekly custody because he was not comfortable around me after I tried to give him drugs a few months prior.  Even saying that his dad had been there and witnessed it, but the boy could not tell his dad what drug it was.  My husband correctly guessed that if I had been offering more than aspirin, he would have noticed.  The following week, the mother calls and is screaming that he has called "her" son a liar.  The story is now that he told his mother I had tried giving him Ambien and told his grandmother I tried giving him Xanax.  The mother said she would only let him have the kids if I was not around.  My husband did not see his children for 2 months, only sees them once a month now, and I have not been around any of them in over a year.  The fact the 2 daughters believed him; I saw as betrayal.  They had known me for 3 years and knew me.  I have told my husband I do not want any of them in the house, ever.  Who knows what the next lie will be, and this was not an innocent lie, but one that could send me to jail.  The daughters I genuinely loved at one point.

How can this move forward, the kid has never admitted he lied, will not even to his dad, and the attitude is that he should just get rid of me, and everyone can be happy again.  He wants to have his kids again, but I will never be around them again.  It is complete disengagement.  

Any ideas?  I would take any suggestion at this point.  Do I just walk from this marriage?  The underlying tension this has created is terrible.  Help!