Regardless vs. Irregardless

Irregardless of the way these two words are spelled, regardless and irregardless have just about everything in common.  Both words are found in the dictionary, are typically used as adjectives, and have the same meaning - having or showing no regard.  Yet regardless of their similarities, the word irregardless originated as part of spoken American dialect in the 20th century (according to the Merriam-Webster dictionary).  This word - irregardless - has eked its way into English acceptability, regardless of the fact many still claim irregardless is not a word.  Regardless of the authenticity of irregardless, as a general rule of thumb, irregardless should not be used in written English.  You should use regardless instead, irregardless of the fact that I have just written irregardless numerous times.  Does that make sense?