You didn't do a thing wrong in advising her to call him on the cell. If he had manned up and told his parents what he was doing it would be one thing, but it's not your place to "cover up" his mess. Time for him to take responsibility for his own messes.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
