I don't have any good advice on telling your wife, but on telling your mother and sisters, I have a few ideas.
Are/will you be able to tell them in person? If so, that is the best way to do it. Since you said they are 800 miles away, that may be a problem.
I have only told a few people not in person, so far, about me. The way that has seemed the best for me (and I stress for me, as everybody is different, and I know others will disagree) was to write a letter, then as part of that letter, urge to call once read for answers to questions. It worked well for my grandmother, as it gave her a chance to read, reread, and process it. She called two days after she read it, and calmly asked the questions she had, and I answered. It gave me the best result I could have expected from her since I was unable to tell her in person.
I started out with some anecdotes that she would be able to relate too, like the dress-up box she kept for my cousins, brother, and I when we were younger, to get her thinking about what might be happening. Then I was blunt and told her. The next bit was a combination of what being transgender actually is (I didn't know how much she knew, so I broke things down barney style as best I could) and what my status/progress was at that point. I acknowledged the need for time to fully adjust, and that I hoped she would accept me as her granddaughter, at least in time. I asked her to call several times throughout the letter to talk and have questions answered.
This is what worked for me. It may or may not work for you, you decide. You know your family.
Good Luck.