You "know"? You know, many (most?) people are surprisingly very accepting. Most will need time to accept and understand fully, but if you do things properly, don't worry about literally losing your family. Besides, if you were to be one of the most unlucky ones who get rejected, worrying about it probably won't help, eh? Keeping lovers is no guarantee at all with the whole issue of sexual orientation, but the vast majority of people at least don't lose -everyone-. Families aren't cemented blocks. People differ. My best friend's dad is being a huge jerk about it (like most things), and her brother is having a lot of trouble dealing with it, but she still has her mother.
You might lose one or two people, but losing -everyone-, I never heard of that, except once, in a family of religious maniacs who would not be "tainted" by reason. And you don't necessarily lose whoever you lose forever.
"I know they won't accept." I think it's been said at least 3 times as often as it actually happened. If you think it'll be difficult, then it's just an indication to do things with a lot of care, explanation and support.
Often, people "lose" family members, not quite because their family member absolutely doesn't accept and shuns them, but because of their own attitude. There was a story a few months ago about a transsexual teenage girl who was always screaming and fighting with her father, insulting him and demanding that he accept it. Whilst it's true it's not our fault, it's still a "blow" we're giving everyone, and just like with most such blows, things need to be done, and they don't include insults.
It shouldn't be, but since the world is imperfect, I think it's the trans person's responsibility to make efforts to help people understand and accept, to some degree. And I think if you fulfill that responsibility, you reduce the risks by a lot. Most people, once they understand it's an "illness" that isn't your fault, and that transition is the only way for you to keep living healthily, wouldn't shun you.
I'd like to give you an example of a similar situation. If a father is homophobic and makes awful comments all the time, and despite that, his homosexual child gathers the courage to come out, the father needs to be an awful person to begin with to shun his child like that. I think a large portion of fathers in that situation, maybe even a majority, would have trouble accepting it, and would gradually change their ideas. The father, enlightened like that, may even become an "ambassador" who'll educate his fellow homophobic and have a positive impact. Like my mother gradually started doing after understanding things more.
If it helps, here are the main issues I think might arise:
-They understand you're a transsexual and it's not your fault, but they don't get why it's that bad. They're going to compare it to simple body complexes, and think you should just deal with it. Solution: Explaining how bad it feels, and how it just cannot be mostly solved by working on acceptance and self-confidence like someone who doesn't like their appearance.
-They think you've been lying to them and feel betrayed. They also wonder why now, since you were fine, from their point of view, for all these years. They might also think you're selfish Solution: Explaining how you feel, simply, and how you really need to do it, and would much rather not to, because you know it's hard for them.
-They think you're mistaken or are making this up. Whether their alleged cause is homosexuality, demons, deviance from God, sexual fetishism or anything else, this means they just don't understand it as a whole. Solution: This is the most straightforward one. Education. Show them well vulgarized, serious, scientific material, such as texts and documentaries, as well as testimonies from both transsexuals and people close to transsexuals. They may choose to deny the facts, but if solid evidence doesn't suffice, nothing will, and they can be labelled as annoyingly stubborn. If they talk to whatever competent professional is evaluating you, also, it should be possible to dissipate thoughts of "I understand this problem, but it's not him".
-They say you will always be a son/father/whatever to them. This, like in mourning for the dead, is probably the denial phase, especially strong for them. They might need to be helped to move on to acceptance. Solution: Asking them why they feel that way and having a heart-to-heart conversation might help. Them seeing a therapist might help a lot too, even if they might be hard to convince, since in their mind, you're the problem, and they shouldn't have anything to do. Then bringing them with you to your own therapist would be an alternative. Without being confronted, they need to come to understand that this is a fact, not something they have control on, and that deciding to deny it is only bringing negativity, like hating the Earth because it spins.
Don't worry too much. For now, concentrate on accepting it yourself. Once you yourself are rid of the issues above and the others I've probably forgotten, you can start thinking about doing the convincing. You yourself need to come to terms with the fact it can't be changed, and go from there.
And yeah, I'm going to agree with the others. Make sure you're evaluated by a competent professional. The apparently contradictory things you say call for investigation and help. Being transsexual is pretty much defined as feeling like the other gender and wanting to be it, right? How What you're saying sounds like "I like ice cream, but I dislike it."
And I'm going to repeat what Alice-blossom said: transitioning is something you should do if you want to; it's by no means an obligation. "Why should I transition?", "Why should I not transition?"... Take these questions and balance your options.
If you have milder dysphoria you are able to deal with, and if transition would bring you more pain than good, well, no one's forcing you to do it. And there are always in-between solutions to make you feel better without impacting your life that might work.
