My boyfriends daughter is starting to hate me?

when i first met radi she was the one that made me feel i could do the family thing because she was so loving and funny. she's 4 yrs old and we used to play all the time. her other sister hal was daddies fav and it took awhile for her to open up around me. well, now that me and hal are good radi is taking advantage of hal's attention towards me and is trying to get closer to her dad. that's what i've always wanted, but now she wont listen to me and started telling me she doesn't love me anymore and wants me to leave forever. that hurt so much because she is my favorite and i love her so much. i feel like she is trying to get attention any way she can and misbehaving is one of them. i don't know what to do.. i don't know if i can staying when she doesn't want me around. i'm pregnant right now and she told her sister she wants to punch the baby. i know she's being like this towards me because i'm strict on her when she misbehaves and we're always together because she doesn't go to school with hal. and i think it's also because she sees her dad shows me a lot of love. what do i do????