I can fully understand your thoughts, anxieties and doubts about all this. To me it was clear after admitting to myself that I was Trans that, I should come to terms with my closest friends and my family as well very soon on what I´m about to do in my life.
That´s why I started coming out to my grandma and my mom shortly after admitting to myself. Subsequently I came out to close friends first after being in therapy for 3 months or so. While my friends accepted me right away, my family except of my grandma, felt somehow overrun and they´re still struggling with it. It´s a hard time for my family and me because I always had a close relationship to them. While my Mom is now at a point where she´s beginning to accept the fact and the inevitability of my transition, my Dad and my Bro are still in denial.
What I wanted to say is, your family knows you for more than 30 years as their son, bro, grandson and so on. And now, suddenly for them, all these "truths" dissapear right before their eyes. They have to learn about Transsexuality, they have to learn what was going on all the time within yourself. They have to learn about your inner disruption, the anxieties, depressions you might have had and you might still have. They have to learn to accept you as their daughter, sister, granddaughter, who you really are.
They need time and they need you to talk with them. In my eyes, there´s no other way. You have to explain your way to be. And as an advice, start it as early as you can. If their mind is ready, your physical transition will make sense to them.
Wish you all the best

xoxo
Anna-Maria