I can totally understand how you feel here. It was so hard for me to come out, because I'm such a shy and quiet person and I don't like attention on myself. and I'm also so not good with confrontational or deep convos either.
but when I did to when I finally had to come out because I was so miserable. I told my sister. because I knew she would be very supportive. And, with my permission, she told a few people for me so I didn't have it. She had no problem telling people that about me.
And then the first few people I came out to, I told them through email or IM. I know that sounds cowardly, but I was scared and I couldn't do it any other way. And you got to do what you got to do.
But I think you could run into some problems if she just "apparently randomly" started calling you "he." I think your family/friends might be like, "who are you talking about?" And then she says "Sam." and then they would respond, "Why did you say "he" then? Is there something we don't know?"
Basically, I think it could become very confrontational.
Another approach, if you want to come out to EVERYONE, just make it a status post on facebook. I also did that recently

It went well.