https://pflag.org/

They might be able to help you better understand.

This seems it would be a huge transition for anyone.  I can see only wanting to involve my parents - not extended people - in this.

The poor kid is going through enough.  It’s great you want to be supportive.  So I’d learn as much as I could and be ready to be supportive when needed.  Until then, step back and let this young person find their own way with their parents (and keep in mind as steps, we aren’t true parents).

Also, what is there for you to fix?  This is someone else’s personal journey.  So I don’t get that last statement.

I agree with the suggestion of checking out pflag and the question about what is there to fix in your relationship.

I also don't think it's a matter of understanding. You don't need to figure out why it happened or how they're feeling that's on the person. Your role should be empathy and support and sometimes that means taking a step back and giving them time to process.

Was there some sort of issue or lack of support that happened that would you lead to there being problems?

She asked if her friend Ash could have sleep over.  I'd always known Ash as Ashley.  and then the next thing I know my fourteen year old daughter has a boy over spending the night in her room.  At first I was going to go all mad parent on her and then I could recognize Ashley in Ash and it occured to me that the little girl from up the street was now a teenage boy and I allowed it.  I figured yes indeedy, he has enough on his plate just being trans and in middle school and trying to navigate his body and relationships.   

Is there a reason you haven't seen your step child in 2 years? What is there to fix? Like was there a falling out when stepchild first came out? 

"Growing up Trans in America" to be very interesting and eye opening.  It was on PBS.  It would at least give you an idea on what the kid is going through and the parents too so you can support your husband and your stepchild if and when it's your turn to be supportive

My mom's husband transitioned to a woman.

For me, there was no real adjustment than calling her "her" and by her new name.... she's still the same person I've known for half my life... just now I get to make jokes about how "I always knew she didn't have the balls to..."

Of course that's within our dynamic, I would never make a joke like that with anyone else.

Doesn't affect me one BIT what bits someone else have... if I was in your shoes I'd just go with it and deal with the kid as the kid wants to be dealt with...(I recognize "dealt with" isn't the best word but I'm too tired to think of a more appropriate word)

Other than their body changes, they're still your stepchild... so initial shock aside, and personal beliefs about the ethics and morals aside, I wouldn't make a big deal about it, because at the end of the day, the only way it affects you is how you call them (he, she, name etc) and what their new likes/dislikes related to gender are (stereotypical gender based likes/dislikes) .

While I went with the flow, it took my younger brother 2 years to speak to her again...and even so, their relationship is not what it used to be.

One of her daughter's still hasn't spoken to him since she told us... see? I wrote him... subconsciously...not going to bother fixing it. She was my stepdad for over 10 years before she announced (actually my mother told me 3 days before facial reconstruction surgery took place), and the transition doesn't change that past. 

Her and my mom are still "married", though only legally... they're more like matching souls / besties now... separate bedrooms, not "together". Transitioning to a woman didn't change the attraction to women (I guess she's a lesbian..?) But my mother is not.

Pm me if you want to chat.