You just have to remember people immediately react by wanting to preserve their own image of you and they don't necessarily think about the person to whom the image belongs, and how they are feeling and what they've had to live with. So don't feel guilty, because other people are just as selfish in their motivations for being upset about someone's transition. Which is what it sounds like your mother is feeling.
It takes time for the stuff to sink in.
Coming out wasn't relieving for me at all, if that helps any. It took about a year or two for people to forget about their concerns completely and initially I was treated with bemusement and indifference from most family members. But after a while they came round to it. If there's proof you always had problems in the past through your writing or your behavior etc. that can also help.
