I posted about a controversial topic on FB and now my mom wants to unfriend me. What should I do?

[Pumpkin Pi]

On Sunday, gay marriage passed in NJ. As a NJ resident, I celebrated by going to a bar and singing karaoke, and then I posted about it on Facebook the next day. I live with my mother, who is an extremely Christian woman. She has a Facebook page, but rarely goes on it. I have gay friends who are getting married, and I'm also bisexual, but I'm in the closet from my mother for obvious reasons.

Well, for apparently NO reason last night, Facebook sent my mother a message containing the post I wrote about gay marriage when it passed (I had written, "Celebrating NJ gay marriage with whiskey, pumpkin ale, and fabulous karaoke!") She came into my room this morning, all upset, thinking that I had purposefully sent it to her. I tried to defend myself, but she said that she thought it was best if I unfriended her so that she wouldn't have to see anything like that again.

I AM LIVID WITH FACEBOOK RIGHT NOW. It doesn't even make any sense that they would send one of my friends something I posted last week. And now they've caused a rift between myself and my mother, especially considering that I'm bisexual. This will make it a lot harder to come out to my mom, especially if she thinks that I'm manipulatively trying to send her gay marriage posts!

What should I do? Who should I complain to? How do I cope?
Sorry, let me clarify. My mother received an E-MAIL in her private e-mail address notifying her of my post. She's never on Facebook. I post a thousand updates a day and this has NEVER happened.

And I know my mom should change her ways, but she is so adamant that it would be useless to argue with her about it. I specifically steer clear of this topic with her at all times, because it just leads to useless fights where nobody wins.