pregnant with bi-racial child

So I come from a very judgemental racist family. I am the first female in the family who has exceeded in academics and has earned the oppertunity to go to college, in hopes of becoming a doctor. Although, this past year was my freshman year in college, where I met a african-american man who I dated for a period of time. I just came home and am 18 weeks pregnant with a bi-racial child. My family has no idea yet (luckily I still look good, with no signs of being pregnant) and I have no idea how to tell them. My brothers all know and are accepting of it and have left it to me to tell the rest of the family. I was going to wait until im 20 weeks and know the sex of the baby to tell everyone else. Unfortunately, me and the father are no longer together, and i'm concerned this fact alone will prove all their "theories" of black men are correct. I want them to be able to accept my little blessing, but have no idea on how to tell them to make it easier. Any suggestions are appreciated

By the way, my parents have always assumed i've dated black men, and have always noticed I have had way more black friends then white throughout my life, so this isn't a new thing.