I think it's different with each person. I don't have a whole lot of insight to give in terms of gaining acceptance over time (I only just outed myself as trans to one of my parents less than a week ago). I do know that when I was initially outed to my parents as gay more than a year and half ago, it took a long time for things to settle back to "normal." Even then, my family has never really accepted that part of me. We simply agreed to disagree, as it were.
I think gender and sexuality are issues that tend to be particularly difficult for others to understand. Some people don't need to understand. Them seeing you happy is enough for them, but for others denial can be their biggest coping mechanism (even in small amounts such as hoping you talking through you're "problem" will make it go away).
Either way, hang in there. Family is always a tough group to deal with because you often inherently want to be close to them. I hope that over time, them seeing how happy living your life as who you really are is enough for them understand.