cooked it ?

Hi Guys, this is another battery question I'm afraid. Getting ready to scoot off in the camper for a few days next week. The other half thought he'd help by putting the battery on charge however neglected to check the water levels first. The charger went through its several charging phases ok. Unfortunately when I checked the battery today- all cells appear dry! So I've topped them up.
The equalised voltage is reading 12.8. I don't suppose there is any easy way to determine how much damage has been done to the battery until we use it and see how much output it has?Thought anyone? thanks, doc.