Quitting job - required 4 week notice?

I accepted a job two months ago and the recruiter and my supervisor very misleading about the job. I gave my notice last week and the company requires a 4 week notice - however I live in Texas which is an at will state. The work environment is pretty toxic and I really don’t know if I can stay for another month. Am I technically required to stay the full month?

I do have another opportunity lined up and would never think about returning to work for this company.

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