That it's not your fault
You couldn't have prevented it
It's okay to feel mad, to feel sad
It's okay to feel jealous or angry or spiteful when you see other pregnant women, that's normal
It's perfectly normal to feel like you want to rage out, like you want to cry, like you don't want to deal with it anymore.
But please take care of yourself. Post partum depression can affect you even with a miscarriage.