sorry to see this easyD-. unless there's wires showing through you only cut through the lip protector layer, i think. i had the same thing happen to me on my conti DW's on weds. i could put a swab trough the tear, no wire showing. i cleaned it with alcohol and glued it up using rubber cement. it held air fine and drove fine until i got my replacement wheel and tire mounted. since it was on my new set of weds i just decided to use the lightly scuffed one as my rear spare.
i think you're fine with just glueing the tear but if you dont feel comfortable or start seeing a bubble on the sidewall replace it. you can't tell the damage on the tire from the outside, so...