I'm certain that, at least at first, my mom will completely reject the idea of me being a boy. She's going to blame my other mom, probably either cry a lot or yell a lot (or both), maybe hit me (though hopefully my other mom will be there to stop her if she does; I won't fight back. I'm eighteen and she'd probably get me thrown in jail. Plus, I don't want to hurt her; she bruises easily), most likely get the whole family involved and have them call me up crying or yelling, and when she realizes I won't back down, she will probably resort to begging. Then when I refuse to succumb, she will banish me from her house and life until I do as she wants. Unfortunately, I won't be a girl for her, or for anyone. It just ain't me.
My best scenario is, she cries a lot, banishes me from the house, and calls me up begging for me to keep in touch after months of ignoring/hating me. I'll take it. Even a mother who hates what I'm doing but loves me is better than one who hates what I'm doing and hates me, too.
This would all be easier if my other mom wasn't trans, too. Then again, if that were the case, I'd either have a "dad" or I wouldn't have been born (if she'd been born right, she couldn't've fathered me, of course). Sometimes I wish the latter were the case.