Ok, don't panic. There's no reason why your Honda CBR250R should get destroyed by the raining season, as it has excellent build-quality. The most important things is regular washing – at least once a week, and at least twice a week when the roads are covered with water. This doesn't need to be a thorough scrub every time – just a good drenching to get rid of corrosive road scum. Avoid crashes by slowing down; and ditch your IRC tires for some with a higher road grip.
It's obviously also important to give your chain a regular clean and lubrication, at least weekly. Use a protective spray, on all exposed metal components, to minimize rust. It's more important to lubricate the cables through the raining season, too, so it's a good idea to give them a thorough service, including lubrication of the pistons, at least once, halfway though the raining season.
The toughest, most durable protection for paintwork is a protective plastic film, I saw some awesome stuff on my last visit to Sampeng market in Chinatown, Bangkok.