Next time it goes offline, just keep it offline. They want to take it offline then let them do so. They'll just continue to do so and they'll be more and more complaints. In the mean time, work with your host and try work with the police at the same time to send any data logs they have to find out who's doing it. By the looks of it, you get a lot of money from donations so try speak to your host about getting stronger ddos protection. My 2 cents.