a) Your friend wrote an incredibly wanky letter. Being the "experienced member of fandom" they state they are, surely they must have been able to predict how wanky that letter would be. You can write a letter asking for torture porn and not apologizing for it without being such an incredible wank magnet.

b) If you don't want to ruin your Yuletide experience I'd suggest getting off coal. Coal's not a monolith, and not everyone here said bad things about your friend, but now that you're participating in the thread under your account name, trolls are going to keep trolling you if they can get a rise out of you. Even if they don't mean what they say they'll talk shit just to upset you. If you're into that, cool, but really, you should probably let it go. (It will also just keep the spotlight on you and your friend for much longer.)