possible identity theft

if someone looks up and uses a social secuitry number only to change an online password, is this a crime?

I don't know what you mean. How do you use someone else's social security number to change your password? Or do you mean you used someone elses SSN to change THEIR password?

Yes its a crime......unauthorized access.

ok so here's what happened. i was dating this guy and he was on his moms phone plan. we were suppose to show each other the phone bill so we could see who each other was talking to. (i suspected he was cheating) So when he failed to do that, I went on his phone companys website and the only way i could change his password so i could look at the bill online was to use the account holders (his mom) ssn and change his password. so i did. i looked it up, only need the last 4 digits and changed his password. i viewed the numbers and logged out. it was wrong and a stupid thing to do and i regret doing it. his mom still doesn't know til this day and this was like 4 years ago. now he's threatening me that he's going to turn me in. first of all, it would have to be her that has to press charges and not him i'm assuming. what kind of trouble am i looking at?