Does my old work place has the rights to go into my personal Facebook without my permission?

[lilmizzrandom]

I recently left my job, and it is at a marketing place and i was in charge of social media, so I had to be on my facebook to work and check up on our clients.

I told MY fb friends through facebook message, why i left.

Now the employee and owner of my old work place are threatening to sue me for telling my friends why i left. But there is NO way they could have read my conversation on my facebook messages that i sent to my friends if they were not on my account. Also ever since I left, I have been getting lots of notices from my email and other accounts I had to use at work, about a third party trying to log on into my accounts from another computer.
i feel like the people at my old work place took the login info of my accounts i had to use at work without my permission, and are going through it after i left.