I just need to talk about this to someone

I have been with my boyfriend for three years. The other night he sat me down and explained that ever since he was a child he's repressed the desire to be a woman. But now he's opening his mind to the thought and would like to consider it. He's not sure, but would like to experiment. I comforted him and explained that it would be hard for me to cope with in the beginning, but ultimately I will always love him and be by his side. The next day I took him to the women's underwear department at the store and picked out some for him. He's been excited and wearing them secretly. Tonight he wore one of my leggings and dresses. I mean it when I say I'll always love him and stand by him. I'm trying to be supportive, but I do feel evil for honestly wishing for him to stay male. He can tell how I feel and we've been talking about it. It's just confusing. I hope no one reads this and thinks I'm against it. I'm just caught off guard. I love him so much. Like I said, we're experimenting and trying it. But I just feel like an awful girlfriend for how I'm handling it.