The tire is pretty much ruined. You could try getting by with a boot secured by some duct tape, but that is taking a risk and why bother at the price? Sidewall flats pretty much mean replacing the tire.

If the flat was in the area of the tread and just a puncture and not a huge gash, well then you just remove the offending object, repair or replace the tube and you are good to go.

Flats like the one you got are pretty rare unless your commute is a war zone or something. You could well ride for years without having another like it.