I'm afraid I have a serious problem. I placed a bet on a team in a sports match where I was a referee
Um, that's not good. Did you know that you would ref that game when you placed the bet?
I didn't know I would ref that game at the time. Also, I wasn't the only one who placed a bet, there were other referees
I understand that you didn't have bad intentions when you placed the bet, but when you found out that you were assigned to that game, you should have declined. In the future, decline refereeing jobs if you know that you can't be impartial.
Can we just forget about this, I don't want to deal with it.
Unfortunately you have to deal with it. It's better to report this to someone in charge on you own, than to let them find out what you did. This was a serious violation, and there's likely to be consequences.