This is an example of poor line management. The better way to start these conversations would have been to ask your view of the way things were going - not launch straight into accusations of bullying before even hearing your side of the story.
You could go back after Xmas on the lines of 'I've been thinking very carefully about what you said to me. I'm as committed as anything to this job, as you know, and if you think I was was over-exorborant then sorry, but really I find it very strange that you chose not to ask me my version of events before launching into you're a bully. By doing so you seem to be accepting newbe's version of events, and I don't think that was very fair'.
See where that gets the conversation.