You did the right thing.
You need to assure your son that you love him. Not only by telling him, but by showing him. It can't seem to be an extra effort because you are "apologizing" for having cock-blocked him, as someone else put it, either. He'll read that in two seconds. You do not need to apologize for anything. Just do little things.
One thing I like to do is go to my cousin's school after he leaves for the day and put a favorite treat and a note in his locker giving him praise and encouragement, or check him out for lunch during the day.
Also, like I said before, kiss him goodnight and tell him you love him and that he is your whole world, etc. Every night.
Parents should do all this stuff anyways.
Of course your son is upset, but he knows why you did it (the real reason is to protect him) and he will eventually respect you for that and love you more when he understands your reasons and intentions. That will take a while, but in the mean time he will get over it.