Computer History & Privacy?

[Amy]

So yesterday, I borrowed a friend's computer for about 20 minutes to send off a job application. Fast forward 2 hours later she accuses me of having looked at one of the documents on her computer ( I hadn't). She basically calls me a liar saying she called Verizon and they gave her the time the file was opened.

I haven't done anything wrong. Accusations aside. I'm now suspicious of her. I access our Wifi on my phone. I'm wondering whether or not my roommate snoops on what I do. Do I have ANY privacy?