Show-cause notice by employer

I am working with a private corporation as a senior trainer. Last to last weekend, I mistakenly posted a statement on a what's app chat group (My team, My boss and My super boss are members of the group). This is the exact statement, " Chu ho Gaye hain humaari company waaley, Saala sister concern bhi Chu hi hogi". I was chatting with a couple of other teammates, after reaching home on a seperate group, when someone posted on team group and mistakenly posted this there. On Monday, I was informed by the HR head and Super boss that the language I used is highly offensive, condescending and defamatory. Therefore, I am being suspended and a show cause notice has been issued against me. I would like to know: A) Can a what's app group be considered an official group, since office colleagues are part of it. I don't remember any such written policy about it. Also, I believe third party apps cannot be used for sharing any official information as they are prone to cyber attacks and there for would violate Information Security Policy B) The language used by me is very generic in nature and is spoken widely between work colleagues. There were no strong expletives used. I have to give a written statement by tomorrow on the show cause notice. Will be really grateful for any help as I am being treated as a criminal by the organisation for this one incident