Your passwords in plain text where not compromised but if you have a simple password it can be cracked. If you used the same password on LinkedIn, Twitter, eBay etc. There is a good chance someone has your password already since they have all been part of multiple data breaches.
Why strong passwords, per unique website, are important:
In the event of any data breach, be it malware sniffing encrypted passwords over the wire, or a database grab of encrypted data, hackers focus their efforts on decrypting what they found. Forums generally use a double md5-hash + unique user salt. This means that, to get your password, they would try one of two ways:
1) Setup their own staging area and try and brute force crack your password with a dictionary file (using software like John the Ripper). This method means they try variations of words, names, numbers and upper/lower case letters. If your password is Helena22, you will be an easy target. If your password is 5v23dWWdg,L!2 the dictionary won't match it. Or,
2) They look at other data sources where they stole info from and already cracked (Twitter, Ashley Madison, Badoo, Linkedin, etc) and match your email address up. If you re-use your password anywhere else, they try the password they have on file first.
The more complex (and unique!) your passwords are for each of the various web services you use, including this forum, the lower the odds they will crack it, and you make option #2 less probable.
-Philip