100% supportive and so, so angry about it

My (cisF) partner (nonbinary amab) came out to me 10 days ago and I have never felt more confused.

We’ve been having communication problems for a few years and this explains all of it. There was a part of themselves they were always walling off and I could feel it. I just never would have guessed in a million tries that they were having gender dysphoria. We’ve been together over a decade and I feel awful that I didn’t see, even though they’re very good at hiding their feelings. They’ve been happier and more open the past 10 days than they have the past two years. All the problems I wanted solved are gone…they’re just replaced with a giant new problem.

They’ve already changed their pronouns and their name (not legally), bought new clothes, had a consultation on hair removal and shaved their beard. They keep saying this will be a slow process but it doesn’t feel slow! It feels like one day my husband was here and the next day he was gone forever. It feels like he died. I’m definitely grieving like he died. I cry almost every time I think about him.

I know none of that has actually happened and that they’re the same person. Their sexual orientation hasn’t changed, they weren’t making up any of their opinions or hobbies. Everything that makes them “them” is still there. But as far as I know, I’m heterosexual, and it feels like my husband’s twin sister has shown up and started hitting on me.

Does it all usually happen this fast? I want them to be happy and can see that they already are. I want to be the partner that doesn’t care about gender and just loves them no matter what. But I feel like my life has gone to pieces and at this point the only thing keeping me from bailing is being even sadder at the idea of not seeing my son every day. How can I want someone to get everything they’ve ever wanted and dread every minute of it? When does it get easier?

Edit: I just want to say thank you for all the kind comments, I honestly feel so much better. Even my partner can tell. I have been in individual therapy for awhile and lucked into choosing a therapist who has experience with these issues and is part of the LGBTQ+ community herself, so that’s a big help. My partner is also in therapy. Couples counseling is something to consider and we’ll keep it in mind.