Today i made an idiotic mistake, i was in a hurry to pack and leave so had to deflate the wing on sand while wet, then took it in to the water to get rid of the sand, forgot to close the valves, realized my stupid mistake too late and now there is water in the tubes :( Tried to get it out when i got home but there is still some water i couldn't take out.

Do you think it will evaporate if i leave the valves open and leave it under sunlight for several days?
Will salt water (probably some sand too) damage the tubes?
Is it better to send to a kite repair shop?

This happened to me on a kite that tomahawked and blew open the release valve. I first inflated it a couple of times, and tried to "pool" the water near the valve, then released the air. This got most of the water out. From there, I just left all the valves open and left the kite spread out for several days and any remaining water evaporated. I don't think its a good idea to leave it in full sun though.

Someone recommended trying to flush some fresh water in there to clean out the salt. I never did it and never had any issues.

Maybe more of an issue if you got a LOT of water in there and stressed the bladders, but assuming it was just a bit -it happens and I wouldn't overthink it.

If you dontbget the salt water out, when water slowly escapes it leaves behind sharp salt crystals. Rinse it out man.

Yes, def rinse the bladder with fresh water a couple of times. It is easy. Make the valve the lowest point to drain and then also roll towards the valve to empty. Pump it up and empty a few times. The remaining drops and moist is not a problem and will simply leave the bladder over time in normal use of the wing. You can sleep well knowing things will be OK.