I saw this as well. It's sad, disappointing, infuriating, and medieval--but, worst of all, completely unremarkable and unsurprising. When things like this DON'T happen, I'm a bit more surprised. Part of me hopes that the late teens and twentysomethings of the world might be the last generation in the US for whom this sort of response from their parents or loved ones with regard to sexuality/transgenderism/whatever is considered anything but the act of hate and cruelty it is. There will always be bigots, and there will always be assholes, but I hope that by the time I'm into middle age, this kind of letter will be seen the same way as a letter telling a child they are disowned for marrying outside their religion, race, or social class. I really wish it would be sooner, but I don't think that's realistic.
Of course, I don't know how realistic it is for this attitude to change measurably in the next thirty years. There are still an awful fucking lot of people my age who are starting to have kids who are mouth-frothingly, fire-breathingly anti-gay.. Maybe THEIR kids will stop carrying the torch of hate and bigotry...