Mother in law always randomly turns up without calling ahead, waltzes in and doesn't take her shoes off and stomps around (I live in a top floor flat and try to respect the woman that lives below us)

Today I kicked up a stink because my wife had gone out and I thought I'd use my free time to play an online multiplayer game which off course can't be paused. Then I get a knock at the door and it's the mother in law unannounced again. I'm really short with her and for once manage to turn her away. I ask my wife if she can have a word with her mum and she gets annoyed (maybe I should of just told the in-law myself?)

But anyways long story short I say we gotta do something about this and the wife gets really annoyed and says 'well it's only a game you were playing so you should speak to her'.

Whether I was playing a game or not isn't really the point. Am I an ass for moaning about random visits? I don't think I am but I have a slightl nagging doubt in my head that's saying what if I'm wrong, hence this post. Thanks