What should I do? Also, what is the law on Boss' searching through employee email?

I only have 1 more chance @ work. My boss got suspicious of me bc I was whispering & decided 2 look @ my work email when I left for lunch, I found out that she read all of my messages in my work email. I had just complained to a co-worker abt the stress that I was in & how my supervisor makes mistakes 2 (it was abt an ignment I had). A few weeks back, I printed out some job positions to the comp which was intended for my boyfriend; it was the same position as the field that I was in. My boss ended up getting a hold of them & giving them to my supervisor. My supervisor questions me abt another job that I may have & I told her that it wasn't for me, that I would let them know if it was. She told me that if I was looking for a job, than it's okay, just let them know so that they can find someone to take my place. ever since then, I feel like i have been watched. I get so tense like they're constantly talking @ me & my faults. My dept is very knit picky. There were some things that were my errors & there was some things that were just knit picking like alphabetical unit #'s or numerical.Today, my supervisor told me that my boss read all of the emails that I sent & that she's done w/giving excuses & covering my back from my boss; from now on, I was on my own (i've been there 6 months).She also gets on to me about putting "the & of" in Owner Reports..that she should not have to double check it for me..(i looked @ hers & there were mistakes!) She said that my job was to "pay attention to detail"...well it's hard when they're so picky! She said that I was supposed to be written up yesterday, but she didn't do it..she said that I've been going down hill since the job posting incident (which was in my Word! & were "supposed" to get 2 15 min breaks @ work & an 1hr lunch) Also, somehow it got down to HR that my supervisor never knows where I am & that I disappear. I know that I have done wrong on some things, but I have never done this before.. i was the receptionist first & loved it, but wanted 2 explore the comp. more..so i became an admin t. in a property mgmt comp (apt).. i didn't even know what a foyer was! my supervisor told me that i had 1 more chance..she also said that if i didn't want to be there then i need to let her knew. she also said that if i cant do the work igned, then 2 give it 2 her & she'll do it herself..she also added that she missed her deadline bc of me & she's never missed a deadline. There's just so much here! I don't like it there..I'm too nice & soft 2 b in business right now.. i'm only 20 & the youngest 1 @ the company..i have a 2 yr old son, too. I'm thinking abt going to HR & telling him my side, so that he can give me suggestions.. i honestly do not want to be there anymore! I don't want to end up soulless. What should I do?! I need a more patient and understanding department who is really willing to work w.me 2 help me understand..not a group who constantly spies on me! oh btw, my supervisor spent an "1 1/2" helping me 2 understand the ignment...& i didn't take notes & they wanted everything organized and grouped. i could do this if I liked my boss's & if they were more willing 2 help (it's also the busiest time of the year)..like stated, i have done some stupid things & made stupid, mindless mistakes, but we're human...but in my dept..we only have 1 chance to correct our mistake... any suggestions out there about what i should do? Also, perhaps career choices? Thanks for listening to me rant!