How do I tell my dad I am trans?

I'm 18 years old and a MTF transual. Everyone knows and is supportive of it except my dad, who is very phobic. I'm afraid he'll get violent if I tell him, but at the same time I can't not. It's getting to the point where it's not something I can hide anymore. How do I tell him without him freaking out? Please please help. Serious answers only