I am so very sorry that you are having to go through this. I know it is upsetting. Many of us have gone through the same thing. The key is giving yourself a time limit to letting all the hurt and anger out and then moving on. Sounds easy but it's not. The problem with holding onto it is that the stress of staying upset will make you more ill now and that is what you have to be concerned with. Sadly you can't change what happened but you can change what happens from now on. Mourn the past. Mourn the losses. Get pissed off and what they did and then try and move forward because you can't let their mistakes make you continue to be sick and that is what will happen if you stay upset about this now.
I had 4 miscarriages and can't fathom what you went through losing a son at 4 days. You have every right to be mad and upset. I just don't want it to make you more ill today.
My thoughts are with you. We love and care about you