In Javier's entire life, he only felt this fear and nervousness now. He can't explain why he feels this way when he should be happy because it's possible that Leona will remember everything.
And the trade-off for that condition is that Leona might want to forget him again. That he knew in himself that he couldn't take it anymore. But he had no choice. This is the punishment for everything he did to the woman he loved.
Because of the incident, Javier took Leona home to their house to show the latter the answers to her questions. There are still traces of doubt in the woman and she seems confused about what is happening. He felt her stop when he finally entered the house so he tiredly looked at her and held Leona's hand.