What do you do if someone took over your guild?

<lj-cut>My sister is our GM and I'm basically second-in-command. We're both very laid-back, and we do NOT want to be tyrants. However, we have another female in the guild who has basically taken over. We really wouldn't care, but *is* a tyrant. And if she's not at work or asleep, she's playing.

She's pushy, she doesn't listen to other people, and she's a know-it-all. She takes over every raid she's on, without being asked. She dominates guild chat, and ignores anything that other women say. She says hi to every guy who logs on and ignores the women. The other women in the guild can't stand her (5 of us). She treats us like crap. But it's very subtle, and all the guys think she's "so nice."

She befriends core players in our guild and groups with them exclusively. She's done this repeatedly, and everyone she hooks up with ends up leaving quietly. We're starting to wonder if it's a coincidence. I personally think she sucks the fun out of the game, and these guys don't even realize what she's done. She's a very intense, hard-core player. We're all very casual she doesn't really fit in with us. Her husband joined the guild, and that's the only reason she's there.

When I first started complaining, my husband kept telling me to just ignore her. Then he saw a few more incidents and now he thinks I should leave the guild. But most of these people are my real-life friends and family. 

What would you do? I want her gone (and so does my sister/GM), but we can't figure out how to do it without her making me into the bad guy.</lj-cut>