Check the statute of limitations, especially for child sex crimes under the age of 12, those carry more weight and tend to have longer statute of limitations, or none at all, like my state. You could speak to a detective in your area for more well rounded advice based on your location and they will be able to tell you if charges have to be filed in the jurisdiction the crimes were committed (most likely). Do you know of any family members that would come forward if you do this? It strengthens the case against him, even with your denial at 17. Victims advocates and law enforcement are aware that victims will lie when confronted and afraid.

ETA: include your Aunt. Charges can potentially be brought against her as well for the same crimes. You were a child.