بسم الله الرحمن الرحيم
When you admit that you have given one talaq to your wife through SMS then one talaq occurred on your wife. It occurred as per your intention i.e. if you have given it in clear cut words then one talaq rajai took place and if you used vague words then one talaq bayin took place. And if you have given talaq in clear words, but did not take her back during the iddah period or you gave talaq bayin; then in both the cases the nikah came to an end.
Note: However the better option is to write the exact words which you used in the SMS for giving talaq and submit the question again.
Allah knows Best!
Darul Uloom Deoband