What caused Stacey to flee into the forest once Papa and Mr. Morrison returned? chapter 12

Stacey ran into the forest because he was frightened for T.J., and he didn't want anyone to see him cry. He wanted to be alone.

Stacey, shaking his head, backed away, silent, not wanting to believe, but believing still. His eyes filled with heavy tears, then he turned and fled down the lawn and across the road into the shelter of the forest.