Annoying SIL - would you confront?

So my husband's sister is a very difficult person. She is judgemental, and yells while criticizing. We ignore each other for the most part. I don't visit my in-laws much, mostly because she Co dependent and always there. But, I feel like such a bad person just sitting there while she's mocking people. It's my nature to stick up for people that aren't in the room. I never do with her, because in the beginning I wanted to get along. I would probably have to raise my voice to even be heard in one of these tantrums. But, I don't want my soon to be born baby to be around that negative energy. I want to say, "wow, that's loudly judgemental," she would learn not to yell around me.

It's always about small things that don't affect her in any way. She always distorts her face and yells for several minutes. I'm just so tired of sitting there like the rest of the family waiting for the tantrum to stop. But, it's never been at me (at least not when in the room... Lol), so it should not bother me, but it's so annoying.

Sorry, for my long story, thoughts?

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