Hi Alex, sorry to hear about what you found, which likely were in place before you did anything. Sometimes the cleaning process uncovers these defects, so obviously seasoning and/or crud can cover them over time but doesn't cure the fact that it is there.
Pan can still be used for non-frying purposes like cornbread, pizza, skillet cookies, even used to brown something and then transfer the whole piece to the oven. Wouldn't use it for cooking anything with more liquid or oil than you would use to fry an egg or saute something. Also as you noted with the SCO, avoid rapid changes in temperature that could exacerbate the crack and exercise caution when moving the skillet around with food still in it.