I'm wondering how to fight a Probation Violation...?

I was placed on Probation/Home detention for 6 months. I know that it only requires a preponderance of the evidence to be found guilty. My first day on house arrest, my ex-girlfriend was texting me and utilizing veiled threats against me...I got mad and made the same mistake back to her. She called the police but called a corrupt officer who lied in the police report, or at the very least left out very crutial exculpitory evidence. I am going to fight the case. I wanted to know if anyone out there was unjustly arrested while on probation/home detention? I can fight it but I don't know how probation violation hearings go. I can prove that the officer did call a different girl I was dating (he lied on the report saying that he "had interviews left to do," and never claimed to have done the interview with her, though he did and I could prove it via cell phone records or even her testimony. Furthermore, I was incarcerated for 45 days before making bail, and they only subpoenaed the text messages after 45 days. My carrier is AT&T and hers is Verizon. Anyone have any idea how long Text message transcripts are kept? And do any Probation officers or lawyers out there have advice for me?