The Words of a Child

Well, technically he is not a child. He is 18 years old, and his only fascination at the moment is D&D! He has D&D games on Monday at a friends house, and D&D here at this house on Thursdays. He used to have his game from 7p to 11pm, but he was asked to change the time to 6-10 because his game takes place in the dining room, which at the present time is Brandon's bedroom. Yes, my two youngest boys are relegated to the couches to sleep, because there is no where else for them to sleep.
I already feel like a horrible human being for not having my own place to live, for having to live with my in laws, for having to ask my two youngest to sleep on the couch, and for deserting my two oldest boys for nine months (from October to July).
But, Timmy has had no respect for my authority in his life since he was about 11, or 12 years old. He has been living with his grandmother for two years, and I have not.
I calmly, without raising my voice, asked him @ 10pm to wrap up his game of D&D. He stated he was almost done. I asked again, calmly, @ 10:30 pm, and again at 10:45pm! He told me he would wrap up and then "we would have words"! I mean who is the adult in this relationship?
Anyway, everyone goes home, and Timmy and I have "words" in the kitchen. He calls me a bitch, not once, but several times. He states he does not understand why Brandon has a 10 pm bedtime. To which I reply, "You do not have the issues Brandon has with his impulse control, impatience, emotions, and ADHD. And Timmy was much more mature at that age (14-15), Brandon is not. Plus, I pointed out the fact that Timmy was not being fair to Brandon, because Timmy has his own room, his own space, while Brandon does not.
I then asked Timmy - after he called me a bitch a few more times - if the other girl's mother was a bitch for making them leave by a certain time. The other D&D game only lasts 3 hours, so why does this one have to last up to four hours? He stated she was not a bitch. So, I asked why then am I the bitch! He offered, "Because this is my house".
Okay, I can understand why he would feel like this is his house, and that I do not belong here. Especially since I basically deserted him, left him here, and left his grandmother in charge of him. But, I am here now! And while I recognize that he does not consider me an authority figure, I find it completely hurtful that he would call me a bitch.
I never raised my voice, I did not call him names or curse at him. Why, then, can he not afford me the same courtesy?
So, I finally heard those dreadful words, "I can't wait to move out of this house!"

OH, I also asked him, when he stated this was "his" house, if he had a job, did he contribute to the mortgage or the bill in any way? Did he perhaps buy the groceries?
All I want is respect! But I also have to realize this is his home too, and mine temporarily. I have to remember he is grown, even though he doesnt drive, doesnt work, doesnt offer to help around the house...Basically does not contribute around here at all.
I wonder, 'What happened to my sweet young boy?'
All he seems to care about is his D&D games! He has no respect for his grandparents, for his parents, his siblings, and a lot of the times not even for his girlfriend! And I soo feel like I am to blame for the way my child has turned out. I mean, sure I can not complain that he is going out and partying, doing drugs, or drinking. But, is it not too much to ask for him to do his D&D game in his room (which is 2.5 times bigger than the dining room or my bedroom), or to move his D&D game to another night?