You need to go talk to your boss, face to face. Don't get angry with him/her, talk and find out exactly why they are letting you go. Make sure you have all your backup documentation (e-mails, etc) to show them too.
There's nothing you can do to second guess until all the cards on the table. You have to show your hand, and demand to be shown theirs, then you can talk, or figure out a way to move forwards. Don't try and second guess this until you know 100% for sure.
