I am so sorry to hear, this has to be shocking at so many levels. Even before the MLC, before having to deal with divorce it is the shock of the sudden loss, even if he was not immediately in your life.
Please right now just be very gentle and kind to yourself, there is so much going on. You don't have to figure anything out right now, you just have to get through the shock and get all the support you can get from friends and family. A lot of things may come back up, as you asked yourself questioning what happened, why, you may even feel you are going through all this all over again.
Just try to get through the next few days. Can you get some mental health professiona support to try to get some footing?