Sure, it is fine to share anything you need to. I'm here to help.
I think support is very important for you right now. It is hard when you are working through a number of traumas, including dealing with your ex. It brings up a lot of feelings and makes it difficult to get through the day.
Wanting to shut down is a defense against all that you have been through. It is a way to say that you have had enough and that things feel too overwhelming. And it might be a good idea, for a short time. When you have had too many things to cope with at once, taking time to turn it all off and get away is good. It can give your emotions a break.
One way you can shut down is by focusing on intellectualizing everything. That doesn't mean you won't feel things, but instead you focus on keeping your reaction to your thoughts and not focusing on your feelings. So when you feel upset about something, do something intellectual. Read a technical manual (maybe something in your field of study), listen to a lecture or figure out a puzzle. By focusing intellectually, you feel calmer. Just be sure to do this only for a break. Using this technique all the time can be harmful by keeping you away from your feelings through repression.
You can also take a break by getting away for a while, even just a day or two. It changes your perspective and gives you less reminders of the trauma you have been through.
Most of all, be sure to keep taking care of yourself. The more you sleep and eat well, the better energy you will have to deal with how you feel.