How do I cope with a douche bag brother-in-law?

He and I have different political views. Any chance he gets, he picks a fight about it. He recently came home from traveling the country for the last 6 months. Last night he invited himself over- this is the first we’ve seen him since he’s been back. He flies in the door, ranting about his politics, and attacking me for some article I posted on freaking facebook. Not “Hi, it’s good to see you all!” but, gripe, gripe, gripe. I tried to avoid it and change the subject which didn’t work. I ended up going upstairs to my bedroom and watching tv all night. He stayed for hours. At one point, I came down for a snack, and he immediately started up again. So, I went back upstairs for good.

Aside from just that, he’s very arrogant, spoiled, and just an asshole in general. He’s 30, and lives at home because his parents coddle him and let him do what he wants.

I don’t know what to do because he’s my husband’s brother and I don’t want to break ties and make anyone uncomfortable. I do my best to be cordial at family events, but he just pushes and pushes. I don’t know whether to just blow up and let him know everything on my mind, or talk to his parents, or do nothing… it seems like anything I do would make things even more uncomfortable. What the crap do I do?

I tried to make this as short as possible. If you want more examples of his assholedness, I’ll provide them.