Recovering access to @me.com account
I got a mail from Apple a time ago where they said that I could use x@icloud.com, x@me.com and x@mac.com with no difference. However, I can't find it right now.

Try send a mail to your @me.com and login to icloud.com with your @mac.com. Did you get the mail? Then, they're all the same account (and have the same passwords)! Else, I hope you did put in an alternative email when setting up your @me.com. Use iforgot and select 'send to alt email'. If you didn't, then you're probably a bit out of luck.

Good luck!