Hi Merryn,
I am sorry that you are going through such difficult phase. I remember how difficult it was for me to come out and tell my parents, and although they didn't were angry, they looked somewhat surprised and disappointed. Imagine the time you took to digest the fact. It takes probably that much time or even longer for others to accept it. Acceptance will come, only it may take longer than expected.
I did not just tell my parents and immediately started transitioning. I had to wait for a year or two for them to understand and show them that I am really persistent with the decision I made and the way I feel. I don't ask you to wait that long, but help you dad understand what you are going through. Send him some links, read some articles with him, and tell him to give you a chance by visiting a psychologist for assessing this. You ultimately need to have this therapy done. I am sure things will turn out just fine.
All the best.
Yashika