Having really bad anxiety

I have 2 kids soon to be 3. My son is 11 he's smart, outgoing, loving and loves to help people of he's able to. My daughter is 5 she's my miracle baby. I was 6 months pregnant with her when my grandma passed away. 2 weeks before I had her my then husband asked for a divorce and tried to throw me and my son out in the cold with nothing so his new girlfriend could move in. Most of her life was spent in and out of the hospital. I watched her fight for her life. Begging god not to take her from me. She's been sick most of her life. But it's been over 2 years since the last serious illness. But now she's in kindergarten so in the back of my mind I'm afraid it's going to start all over again. I'm due November 15th with another little girl and I'm scared. I know I will love her as much as I love my other two kids but in the back of my mind I think about everything I've been through with my baby. Any advice would be great thanks.