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If you sent the form to him, notifying him that he has been revoked, then yes he is no longer legally your power of attorney. Revocation ends that authority.
If he tries to act as the power of attorney now, he's committing fraud.
Now, that being said, I would also send a copy of that revocation to any of your financial or medical institutions (depending on what the POA was for), so that they are made aware that it has been revoked. This is not legally required. It's just a smart thing to do. So, I'd send one to your bank, your doctor (if it allowed for medical decisions to be made), your investment broker, your insurance company and to the bank holding your mortgage, etc.