I really need help, because I am so angry right now.

First, a little about my situation. My husband and I barely knew each other when we moved in together (5 months into the relationship). Within one month, his sons who at that time where 11 and 14, moved in as well - let the fun begin!
So, we all learned to adjust and go through the terrible teens with the oldest. When the oldest left for college, the youngest started to get in trouble - first he was caught with Pot at school (14 years old), kicked out of the school and was enrolled in a private school. Things were quite for a 6 months, then he was caught with a girl at 4:00 in the morning at a park and it was 25 degrees below.
Things got quite again - at 16 1/2 his father found that he was still smoking pot and grounded him for the whole summer (sorta of, the kid was allowed to go to a concert, go visit his girlfriend and etc) to no surpise senior year of high school, he was caught smoking at school, accused of stealing money from another student and shoplifting. I am telling you the child was never punished, we are paying for his shoplifting ticket and the kid continues to party and ask for money from us constantly. Everyday is a fight around here, when his father is at work the kid argues with me about everything and if I say anything to my husband, I am accused of lying or I do not like his son, or that I am causing problems. The best part is when the kid argues with me, he will often call his father at work and lie to him telling him that I said this or that. Lastly recently the kid has been smoking pot in our house before school, when I mentioned this to him I heard-how do you know or really sarcastely thats awful early to be smoking pot! Like I am making up stories again.

Any advice? I love my husband but he needs to support me as well. I just don't know what to do - I have thought a lot about leaving (we have been married 3 years, together all total 7 years).