Done 11 years of martial arts, including Muay Thai. Played rugby union in the front row after that.
He will get hurt but that comes with the sport even while training. At 16 he has grown enough to deal with that.
Why on earth do you did you leave your 15 years old alone in another country?
Now you are paying the price of emotional neglecting him. Can't go till April because of work? One of you should go anyhow and sort this out personally.