How did my boyfriend hack my facebook chat?

[irritated]

Please don't tell me that it can't happen because he did. He didn't install keystroke software onto my laptop because it's a work laptop that he has never touched.

He has no access to my laptop. He printed out word-for-word my chats without my password, without my laptop. HOW?!?!?!?
I change my password periodically, and he wouldn't know it. He's too cheap & computer illiterate to purchase keystroke software on his computer. Whatever he did must be simple or he wouldn't have done it. I found something about using javascript code plus a person's facebook userid number to see their chat history just by pasting it into the url window while you're in FB. I bet that's what he did. I'll just have to use it myself for a while & see if it works.
Oh yeah. I use Mozilla and a Mac. He uses a PC.
And, if a 12-year old can hack it, tell him to tell me how it was hacked so I know how. Thanks.

[jojo]

change your password to be sure