Feeling depressed today

I am 9 months, so almost there. But today I am feeling depressed and wondering if we made the right choice having a baby right now. It's nothing to do with us or the baby, we are already so in love. It's to do with my mother and step father, I don't know how to set boundaries without her blowing up on me. I don't really like her, she is verbally and emotionally abusive and I am resenting her right now because she is causing me to not be excited for my baby. I am afraid they are going to intrude on our lives and I will be depressed and not enjoy this special time in our lives. I just want her to leave me alone.