Give yourself permission to be a basket case. Try not to pass judgment on yourself or your process. Let the grief, sorrow, abandonment, anger, whatever it is, flow right through you without resisting it, when you can (not when you're driving or teaching, because this requires that you have no distractions). When you have some quiet time, let it in, let it be as big and bad as it can, let it give you its worst -- and it will flow through you, and it will hurt, and then, if you really don't fight it, it will diminish, and diminish, and diminish.
Here is a poem I wrote after my mother's death in '87. She had emphyzema, and had been on oxygen, and going in and out of hospitals for so long that I somehow thought she was never going to die, she was just going to by "dying" forever.
After Death
Since you died, I have woken every day. That has been the hardest part, that instant When you have to be deadened again -- Not killed, but given back to death. I smother that hopeful sense That clings to me from sleep. I send you back across, or I cross, myself, The swirling black that swims around the dream.
This is only a matter of seconds. Then the day proceeds. This is the real work of the day. The rest, routine.