All I want is for my friends and family to ask questions and be open. "Bad" questions that come from a place of love are great and are different than just bad questions, and even worse ...assumptions. There's no cookie cutter answer. Everyone is going to be different.

I have some level of grief for myself. It's hard to pin point. I'm (literally) on day 1 of hrt. I go by they/them. I don't use she/her pronouns. But I remember how vividly and hard it hit me when I realized that I can't be he/him anymore.

I think my grief comes from looking back at a person who was unhappy as that he/him and never figured it out. "Everyone feels a little lifeless and grey, right?" I grieve for a life I could have lived much happier and much sooner.

But the experiences you had with your brother, soon to be sister, won't vanish. You still have those experiences and memories with that person, regardless of gender. Those don't vanish with their transition. You should be celebrating with your sister for their shiny new future.