It will get better Billie.
That is a massive thing to take in. Death is not something we have been taught to deal with in our culture. As a result we don't tend to cope well in the face of it. Add PTSD to the mix and I think your doing extremely well to even be posting today. You have found words. This is good.
We will lose our shit over and over again, but each time it happens we start to remember how to clean ourselves off and brush ourselves down, have a quiet moment in the corner while compiling all the fragmented parts of our mind and when we are ready, get back up and face life again. It's hard but you are strong.
Take some time for yourself. Must you go to uni tomorrow? Please take care of yourself Billie. You deserve some caring.