my wife recently had an affair. I found out about it from texts on her phone. How can i get all the texts pertaining to her affair from the phone co.

I don't know for certain, and I suspect that this is a phone-company-tech question more than a legal question; I wouldn't count on being able to recover the actual text messages she might have sent or received.  But records of the times and dates and phone numbers, for all her sent and received text messages, might well be possible, much like getting voice call records (but not the recording of the calls themselves).  Either way, you'd have to file for divorce, and then subpoena the phone company within that case, unless the phone is on a shared account (in which case you should be able to request the records directly).