Acts 16
31 So they said, “Believe on the Lord Jesus Christ, and you will be saved, you and your household.” 32 Then they spoke the word of the Lord to him and to all who were in his house. 33 And he took them the same hour of the night and washed their stripes. And immediately he and all his family were baptized. 34 Now when he had brought them into his house, he set food before them; and he rejoiced, having believed in God with all his household.

So the guard does not kill himself. Instead he gets saved. His whole household actually receives Christ and is baptized because the guard brings them to his house.
I have to wonder if the guard brought them to his house WITH approval? Otherwise that would have spelled a death sentence for the guard.

Something I read on another page:
a. Paul and Silas did leave the prison (in the protective custody of the jailer) to minister to the jailer’s household. But Paul and Silas returned to the prison willingly to spare the jailer certain death.

Acts 16
35 And when it was day, the magistrates sent the [e]officers, saying, “Let those men go.”

36 So the keeper of the prison reported these words to Paul, saying, “The magistrates have sent to let you go. Now therefore depart, and go in peace.”