Submit a webform like I advised you to . It's not a big deal, mistakes happens all the time but you should correct it. Whatever information you provide to CIC will be in your file forever, so it's better for you to correct the error.
Just send them a webform and stop worrying, there are more serious cases than yours and there was no refusal.
If you don't correct the error then nobody can tell you what the decision of the vo will be, if they find the error themselves they might request an explanation from you. So it is better to address the issue yourself , send them a webform and that's it. They will never deny you for telling the truth, it was a mistake , you ticked the wrong box and contacted them when you discover, they will not deny your visa for that. They like people that are upfront and honest.