How to break the news to my abusive father plz help

Alicia
My father is abusive I don't live with either of my parents because one day my dad decided he didn't want me anymore and so he threw away everything I had I worked for I payed and left me with one outfit the clothes I was wearing and decided to drop me off with my homeless mother we were living in a foreclosed house with no electricity no food no anything. My mom as lays left me home with my four old niece who I had to take care of and find ways to make sure she ate . Well one day I ask her if I could visit my bf she said yes not even 24 hours I was gone I get a call saying I need to come back pack what I had and leave and figure out where I was going to live what a mom right !!! Now I'm in a home living with my bf he is 19   Almost and I'm 18 almost and pregnant the thing is my dad is trying to become a better man and wants me to come down for Christmas but if I go down I would be showing so he would find out.  Should I not go down? Of should I just tell him instead of him finding out and being more angry but I have to think of if he goes after me that would be putting my unborn child in danger. Any advice