Maybe you can set it aside for a bit and come back to it later? I know there are things we understand only upon reflection - that we are too close to them initially to see them clearly.
If you can just be gentle with yourself and allow yourself to "sit with" being tearful sometimes, I think the answer will come later.
Our minds are frequently busy beneath what is happening obviously. I have to believe you're processing some of the too-hard-to-face-now things underneath your everday functioning. And some of it hurts even when you're not aware it's there.
At least that's my guess.