If you are a minor and under their roof and they are homophobes - you are very smart to not tell them anything at all. They could kick you out, send you to a program to turn you straight and make your life miserable. Don't tell them until you are at least no longer a minor - ideally when you...
You had good intentions. But their are different types of people out their. I would explain to your supervisor why you did what you did and just leave it at that.
What if this guy thought you were trying to undercut his hours? What if he didn't have a lot of work to do anyway and you helped...