Question for teen moms...

Grace • 18 - FTM - due date is Jan 26th 2017
I turn 18 in 5 days, I'm already done with high school, my mom's knows I'm pregnant I just found out yesterday, took a clear blue today and saw that it was 3+ weeks along. I'm really close to my mom so it wasn't hard telling her what so ever but my dad is a different story. My mom said, "do it on your time" (they're divorced btw and I only live w my mom don't talk to him much) but my dad is very abrasive and has always been tough on me and I'm REALLY struggling with the thought of telling him, I'm at a loss I don't want him to turn his back on me, I'd be heart broken. How did you go about telling a "difficult" parent?