bad week

Honestly this week and a half have been some of the most frustrating yet.  I got caught up in a situation at work where I got written up for a major mistake. Yes, technically I made the mistake, but I made it because someone else lied to me about what they got done.  They wrote me up and proceeded to tell me that I was distracted on my phone.  I most certainly was not, but I was caught in a "my word against theirs" situation.  They gave me instructions on how to proceed, I followed them, but apparently followed them too specifically and they expected me to broaden the definition.  Basically they told me not to use my phone in front of everyone,  I did not, but they thought I should have taken it as "put it in the car do not take it out again," and wrote me up for using it. It also didn't help that Facebook showed me active at the time (sooooooooo not true, but internets are screwy).  Finally I found out what happened by talking to my coworker who was also there that day.  Turns out she was not explicit enough in her instructions to me.  She told the managers that she told me to do something, when she in fact did not and her "reminder" was extremely vague.  It was determined that I should have understood the instruction, and again distracted by cell phone did not leave their minds.  I cannot use those discussions with her as "testimony" because she and I were both directly instructed to not speak to each other about it.  She was kind enough to do so though, so we could clear it up because we were equally confused.  They declared it "case closed" and won't hear of it again.
This is one of VERY few times where I have been caught in a situation where someone else is pointing at me saying "you did this there is nothing you can do to convince us that you didn't."  and "you're lying, quit lying to us it's just making your situation worse, tell us the truth."  But I DID TELL THE TRUTH.  they just won't believe it under any circumstances. Now suddenly I've gone from having a decent job I enjoy and have a good relationship with coworkers, to probably getting fired and losing the trust of no fewer than three people.  All over something I had no control over.  Nobody will listen about it, nobody will do anything.