I struggled really bad when I was pregnant. There were a few times I had full blown sobbing panic attacks and I was convinced I was going to go into labor early and kill my baby. My daughter is now 17 months old and perfect.
To be completely honest, I was in a very bad relationship and in a very bad situation. I didn't begin to feel better until I left my ex when our daughter was 5 months old. I don't know your situation but think about your life. Is there something or someone you need to cut out for your health? A person? A job? Sometimes a hard decision like that needs to be made, and you grieve, then you feel better.
If that's not the case (and even if it is, you can still struggle), consider therapy and/or medication. I'm not saying pop pills, especially while pregnant, but there are some safe ones you can take that can make a difference. Look at it this way: Depression and Anxiety Disorder are illnesses. Your body doesn't make enough "happy" chemicals or makes too many "anxious" ones. You can "get over" something in your mind but your body does not allow itself to relax because of a chemical imbalance. All the logic in the world "There's no way that ambulance was going to my kid's daycare. It's been twenty minutes and I'd have been called by now." does no good because your body is pumped FULL of chemicals saying "OMG OMG OMG PANIC" (or "Nah man, you're miserable and helpless. Cry forever even if you don't know why and you know you have a good life. Cry anyway.")
There is no magic pill to fix your life, but if making changes to your life doesn't work, and therapy or talking it out regularly with someone you trust doesn't do the trick, it can help you COPE not having to constantly fight logic vs. what your body says.
I've had it. I have to pay more attention when I'm upset how I'm talking to my son. It helped alot. Try to relax and do more things that my u happy. For me I had to get out the house I was getting more down by being in the house all the time.
I hope you get better with it god bless you and your kids <3 (: