My partner came out as trans. How do we explain it to a 3yo?

My partner recently came out to me as trans (MTF), it wasn’t much of a surprise as I knew I didn’t marry a cis-man. She is slowly taking the first steps in transitioning but we’re unsure how we would broach the subject with out 3.5yo.She is currently reaching out to therapists but because the holidays are so close we’re not expecting to hear back until after.Are there any trans parents who went through this and can offer advice? Book recommendations? I’ll take anything really.An added layer of stress is that we know her mother and siblings probably won’t be accepting and depending on their reaction we won’t allow them to have a relationship with our child so we may have to explain that as well. via /r/Parenting http://bit.ly/2ByJEY1