Need advice for dealing with family.

First off, forgive me if there is another post dealing with this, I did searches and came up dry on this. I could have used a wrong search terms, but hey, I did the best I could. :D

Anyway, a little background info. I am currently in a commited relationship with a male to female transgendered woman, and I am female, we consider it a lesbian relationship since she's been on hormones for over 7 years, and has been diagnosed with a gender disorder, this isn't a passing fancy for her. The only difference between her and a biological woman in mannerisms, outward appearance, voice, clothing, etc, is that under neath it there is a slight anatomy difference, that due to hormones, is not hardly even worth mentioning.

We have been dating steadily for 10 months now, and met online through a dating site (95% compatability, WOOHOO) We get along famously, our relationship is honest, loving, and one which should last for the rest of our lives. We are both over 40, and have been in previous relationships that didn't work, (my previous serious relationships were all hetero, though I've always considered myself bisexual) but this one just seems comfortable and happy. I can honestly say I love her a little more every day. We are hoping to get married next May when she finally gets her degree. She'll be the the one in the dress, and I'll be in the tux LOL!

Anyway, onto the issue. The issue is with my family. We were not going to tell any of them she is transgendered. What anatomy she has is none of their concern. They seemed quite fine that we are in a lesbian relationship. All was well, till.... my brother saw a post online where she was speaking on being transgendered. Now that he knows she has some male anatomy, the proverbial poo has hit the fan. He won't allow us to come over, and doesn't want her anywhere near his two little girls, which is really sad, because they love their new Aunt, and she loves them. He found this out today, and I have yet to tell my sweetheart about this. I don't know how to tell her, or if I should, or how to handle any of this.

My grandfather left each of us grandkids a house in the same neighborhood, so we live right next to each other. If we lived further apart, it would be a small annoying issue, but I'd be able to protect my girlfriend better. However, we all see each other every day. All the houses titles are in one name, my fathers, till he passes on, as per my grandfather's wishes. So selling the house and moving away isn't an option either.

This is all new to me, I've never had to deal with this sort of problem before. I am hoping for help from any of you who might have some insight into this. The answer is probably obvious, but to me, I haven't ever had to deal with this before. I understand my brother's pappa bear protectiveness over the children, but there has not even been the slightest hint that she's even a bit of a danger to those children, unless smiling them and hugging is considered dangerous. For the record, if I thought at all she was a danger to children, I wouldn't be in a relationship with her. I always considered it a non issue.

I am really angry at my brother's closed minded reaction. There is 10 years difference in him and me, I am the older one, and I feel I raised him better than that! I have not lashed out at him, I was sort of stunned by his words. Family is important to me, and I'd like us to all at least get along. Why can't everyone just treat each other on an individual basis? How wonderful would the world be then? But alas... tis not to be so...

Any insight, advice, thoughts would be greatly appreciated. I'm stumped.

Thank you!