Do what I do. Keep in mind that, despite the ranting and tension, she gave you your wife, and that in a very short while, you (and wife) are going home. And your FIL is stuck with MIL forever.
Let me guess.. you’re in the early years (months?) of marraige, right? Once you’ve got some experience, you learn to take the hysteria in stride.
Meanwhile, enjoy the scene!
Oh, and one more thing: NEVER say a critical word about either in-law (mother, sister, brother) to you wife. Even if she initiates the rant. One peep out of you, and it will come back to haunt you. Maybe not the next day, maybe not next month. But there is NO forgivness in this area. None at all.