I'm scared, and it's eating me inside...

I was raped by somebody I trusted while I was in a relationship with my current boyfriend... I ended up pregnant.. I had the baby.. and now we need DNA for legal reasons.. and as bad as I want it to be his, I don't know that it is. And it's eating me away inside as he's already so attached to her... I can't tell him...
It was my brother. It was my brother who raped me. And as beautiful and healthy as my baby is, she needs a dad. And I never want her to be known as the inbred girl...
I couldn't abort her. She was apart of me the moment I found out I was pregnant.
Nobody knows about the rape, and I don't know what to do.
I see him in my dreams. I have flashbacks. I cry for hours and hours... and I don't know what to do.. it's eating me alive...