Quitting At Will Job

I emailed my boss my letter of resignation to quit my job effective immediately and he replied calling me “disrespectful“ and “leaving in bad standing.” He said me not giving a two weeks notice is “burning bridges”. Our employee handbook states that they are an “At Will” employer and I have a right to leave without notice or reason. Do I misunderstand what “at will” means and should I just give them a courtesy two weeks?

I have another job starting in two weeks, it’s higher pay and better schedule. I did not state this in my resignation letter. Im so tired and just wanted break before starting.

Edit: My new job is in a completely different field that aligns with my degree.

Author: Practical_Tune_5637