I went through this process against my father. Ultimately all those worries you have, I had but the crux of it was that if I didn't try and pursue justice for myself, no one else was going to anything about him. I would have felt like I was allowing him to get away with it and more importantly, by implication I would be feel that I was saying to myself that I wasn't worth justice. The thought of not having tried would have haunted me.
However, it was not easy. I was trying to cover 6 1/2 years of abuse. I made the statement on my own, no professional support, no company. I struggled with chronology of events and dissociated etc.
The fact is the police may not believe you. But have a right to be respectfully questioned in the presence of legal or supportive counsel. Not bullied or interrogated. You are after all reporting a crime not a suspect. It may be of course that this person (do you know the guy who raped you?) has history for this kind of thing.
One of the things that I got some comfort from was that my Dad was picked up/taken from his house (hopefully people saw) and was taken into questioning on more than one occasion. He was arrested. I bet that shit him up because he had been getting away with this for a long time. It might have not made it to court but the Detective who questioned him said that she they had no doubt of his guilt.
I don't know if the fact he was questioned in relation to child rape and sex offence stays on file but that town is a small place. I hope he's paranoid as hell.
A thing you should consider that if you do this, it may help someone in the future if he does it again and sadly if he does and that woman comes forward her testimony may help yours. It's a screwed up, revolting state of affairs to consider but that's what society see to do for sex offenders.
You DO have pictures, you do have your youth group leader as a witness and support. The fact you denied anything happened because you were scared of it leading to having to face him or repercussions from him at the time, is something a trained sexual assault unit officer should understand. Your youth group leader should go with you.
Anyway, I would say don't think of the possible failure/s. Why is it that you need to do this? Are those reasons strong enough to drive you through anyway. If it is that fundamentally important to you you'll have to do it anyway, no matter the potential cost.
Good luck, your very brave to be considering this. Get support. You deserve justice and society needs to catch up on how this stuff is policed. The more people that can come forward the better.