I haven't come out to my family yet... partially because I'm currently only with one person, and partially because I'm a coward. At this point in my life I'm dealing with some pretty serious health issues and don't think I have the emotional strength to deal with that conversation too. Someday I'll probably feel differently, but I applaud you for being brave and honest about who you are and who you love.
That being said, I thought Dan Savage had some pretty good advice about coming out. He actually said it about gay kids, but it applies here too. He said give it a year after you come out for things to settle down and for your family to sort of get used to the idea that you're not living up to the same societal standards that they are. Give them time to adjust to the new reality. Don't push them, don't try to educate them. That's something they have to do for themselves. If after a year they still reject you, make a new family. The best weapon you have in your arsenal as an adult child/sibling is your presence, and you should not have to hide who you are just to make sure that they can stay within their narrow comfort zone. As another poster said, make a new family. With your partners, friends, whoever loves and accepts you for the complicated and interesting person that you are. Blood means nothing.