"the holidays are very one dimensional and boring because all they do is drink. All 3 of the sons are going to be there this thanksgiving and arguments breaking out will be inevitable (ughhh). The one brother who lives far away particularly drinks a lot like first thing in the morning and seemingly lives to push people’s most deepest and sensitive buttons."
This sounds like a nightmare. I think there are probably several people in your husband's family who have serious drinking issues, and I bet that's why your MIL is so fixated on alcohol. I'd bet big money she's an alcoholic herself, or at least on the way to it, and is in that denial/conflicted stage that I remember SO well in myself. There was a LOT of joking about drinking, and focusing on my consumption and that of others. I was trying to come to grips and at the same time denying to myself and others that I was in serious trouble. The joking was a defense mechanism. "Oh hahaha look how much we all drink, isn't it funny, it's just who we are and if you don't drink like we do there's something weird about you." That's how my friends and I behaved. But deep down we all knew we drank way too much. I am the first one of my (small) friend group to quit completely. But just about all of them have cut way back, and a few are on the verge of quitting. I don't hang out with the old friends who still drink like I used to. BORING.
Can you limit the amount of time you spend with your husband's family over the holidays? Tell your husband how uncomfortable the comments and drunk arguments make you? If He's supportive of your sobriety he will understand that.