Is it illegal to print and read someone else's text messages and private facebook messages?

[Jordan]

My girlfriend's mom has connections with people in the phone company so she got my girlfriend's, who is 18, text messages in print and after reading them decides to hack into her facebook and read her messages between her and myself. After reading all the messages her mother became furious and threatened to take my girlfriend out of college. Her mom dosent pay a cent for her to go to school, but that's besides the point. My girlfriend and I both hate her mom so I was wondering how, if it is, illegal it is to rear someone else's text and private faceook messages. Also what the penalty is.. like a fine or jail time.
My girlfriend has straight talk through at&t so she buys the cards at walmart her self. So her mom pays nothing for her