You may not be that bad. If the iphone is working except the SIM Slot it is likely you have just a small crystalization of the minerials in the water across 2 of the SIM connectors inside.

If you can get a small hard bristle paint brush or customise something you can slide it down the SIM hole and move it around to break that up. DO NOT USE WIRE BRUSH...

There is nothing your going to damage down there unless the brush is to wide or metal bristle.

Something to try and good chance you will get it back. Let me know if this works for you. PM if you need more info. Thanks.

I also double in electronic component and circuit board repair.

Thanks.