ok i have to say that regardless of the WHY it was absolutely poor form to contact her work for any reason and especially to announce an affair. inexcusable.
however i understand what pushed you towards making that rash decision. you have accepted the unacceptable, tolerated the intolerable and allowed yourself to be abused for years. your wife is not a nice person, and takes it out on you and then gets away with absolutely wretched behavior.
i think if anyone is giving "notice" it should be you bailing out on this farce of a marriage. she has shown you who she is and what she is about. and it isn't pretty. she isn't going from multiple affairs, belittling you and drunkeness to kind, loving and thoughtful - EVER.