Dumbledore... Gay?

I know that I'm late getting to this, but since no one reads this, what do I care? J.K. Rowling has announced that old Dumbly is gay. This is not the first time she has made announcements about characters after she supposedly finished the series. I will admit, that her first announcement was welcome. I was excited to get more info on the characters. However, this last announcement bothers me.
I think I am most bothered because it feels so absolutely irrelevant. Let's think about this for a second. We read seven LONG books about these characters. If was never important enough to bring up in the stories, then it is not important enough to bring up post-story. It doesn't help me understand him better, or his motivations. The only thing it does for me is serve to kind of disturb me about his relationship with/interest in Harry.
Another issue that I have (and that is brought up fantastically in the NY Times' article linked above), is that I don't believe that he is gay. This isn't some stupid hetero-denial of his life. It's is just not supported in the text at all. The only basis for this claim, is that Rita Skeeter very cryptically suggests it (and her suggestions are made to feel absolutely ridiculous anyway). If you are going to create a character, then be proud of that character. If your character is gay, then make that character gay (and I don't mean flamboyant, I just mean believable).
My beef is that I have an invested interest in these characters, and I went through seven books (each of which I read at least twice, most more than three times), and grew to understand each character in my own way. To come in, after the fact, and make statements that are unnecessary (how does his being straight/gay matter to what is going on?), and unfounded rocks my foundation and turns me off from the book. The characters were believable. Now, she is taking that away from me.
I hope people understand what I'm saying--his sexuality is irrelevant. I don't care that he's gay. He's her character and if she wants him gay, then make him gay. My problem is that she never made him gay, and expects me to believe it just cause she says so. What this feels like now, is that she is either needing attention or has an agenda, and frankly, I don't care about her agenda. I care about these characters.
I have a solution: if she really is just feeling like she didn't do justice to these characters or something, and just needs to say more about them, then write another book. I don't mean a novel. I mean, do something like The Silmarillion or something. Write a book that allows you to do back story or acts as an appendices. That is the only way that I will accept any outside information on it.

It's like Lost. I don't care how many outside interviews that the writers do explaining what is or isn't going on. If it is going on, then put it in the series clearly (at some point--I'm not calling for immediate answers because the show is fantastically successful at what it offers: questions), and if it isn't happening, then make that clear.
To what may we turn to more fully understand a fictional text? As a writer, you need to believe that the reader will need nothing more than itself.