It would be the unusual person who wasn't anxious about starting a new job, especially after a bad experience in their last one.

Even though you are anxious, try to allow your mind to be open to things about this new job that you might like. Who knows? Maybe that new boss did you a favor but you just don't know it yet. But if this new job isn't the one for you, you can look for a new one. That 'I've got to make this new job work out, etc' kind of thinking just adds pressure.

Ask for any support you can get while you are going through this transition. Let us know how it goes.