WTH???

So, I decide to allow my 18 year old nephew move back in with us.(he just turned 19 today). We kicked him out because he got physical with my husband. He has been back with us since August and things were going along well for a while. He works(2 jobs) and goes to school. He has given us $50 towards groceries and $250 toward rent. This was in August. He eats like Jethro and does not care if anyone else in the house gets to eat. He lost his house key and has not had another one made, and that wouldn't be a problem if he didn't get off work @ 2 or 3 in the morning. Which means one of us has to wait up for him to get home. He uses our car, occasionally, but will only put in enough gas to get where he is going and back home. Did I mention that we drop him off at the bus station everyday so that he can get to school and he gets angry when we won't pick him up after school. The real problem is that he has begun to disrespect my husband. Not in that blatant out and out type of way, but more low key. Like he may ask the two of us a question and my husband will respond(usually one he doesn't want to here) and my nephew will position his body so that he is no longer facing my husband and continue the conversation with me(after rolling his eyes). When I do something for him he says thank you, but when my husband does something, he says nothing. My husband has said that I need to have a talk with my nephew but I am not sure what to say. My nephew is constantly making bad decisions and not taking responsibility for them. He won't hang around his mother because he doesn't like her new husband, he has burned bridges with his grandparents and he gambles away his money(betting on bowling) and he expects everyone else to take up the slack for his mistakes. Instead of taking his money to purchase a needed book for school: he gambled away half of it and had the nerve to ask me if I would help him purchase his book. Just yesterday, he did the most stupid thing: he has lost his house key, my husband, myself and the kids were pulling up in our drive-way and noticed that the trash had been set out. Well, we didn't sit it out before we left and my nephew was not at home when we left. Well, out of the house steps my nephew and at the top of his voice he says" yeah auntie, I got my b&e skills from you!" I'm like what? How did you get in the house? He climbed into the back window! The only window in the house that does not lock! He stood his big ass up on the cooler, lifted the window and climbed in! I could not believe it! Then he has the nerve to say that no one saw him....WTH????? Of course someone saw him! I had to keep my husband from cussing him out and I had to calm down because now you have put the entire household in jeopardy! When I explained this to him, he looked at me like I was stupid. He thinks it was okay to climb into the window and expose us all because if someone does break in while we are home then he is going to fight them! A bomb could go off in the middle of his room and he wouldn't hear it! So, I don't know what my conversation to him should consist of and I don't know if I should continue to let him stay . He has no place else to go and I just want PEACE in my house.