nothing i have said is untrue. a founder of a company leaving to compete out of greed is a bad thing and i am glad to call it out.
In case you were unaware, if someone's defense against being called an asshole is to say "well nothing I said was false" they're almost certainly an asshole.
No one accused you of dishonesty.
Did anyone say you said anything untruthful? No, they just called you an asshole. You can both be an asshole and be right.
PS - Just some advice that I learned in sales 101 early in my career...focusing on shit talking the competition generally isn't a strategy that works well.