I'm truly sorry you're going through all of this. It sounds as though you are dealing with a lot. I trust you've spoken with a doctor about the headaches and excessive sleeping? I would echo what others have said about speaking with a counselor or therapist, if you haven't already. Someone who specializes in trauma and grief.
And please be sure to treat yourself with kindness and compassion. I can tell you with my own experience with trauma and grief that there was a time several years ago that if I managed to get out of bed, brush my teeth or shower then I counted that day as a success. And if I didn't manage that or anything else, then I allowed myself that space. You don't have to figure everything out, just find a way to make it through each day and let the past and future take care of themselves for a little while.
So while I can't tell you specifically what you should do to feel better, I can tell you that what happened in the past happened, and what has changed in your life has changed, and, unfortunately, yes, whatever has been lost has been lost. But some things have not changed, and some things can never be lost--you are still here, you are still strong, and you most definitely have the chance to be happy again, possibly in surprising and wonderful ways. So hold on and take that chance.
I wish you all the best and be sure to keep us updated on how you're doing!