Individualism and cooperationism/collectivism/communism/communalism/communitarianism (yes, these are five different things, but victims of the capitalist propaganda machine will think of them all as variations on the same collectivist/communist theme, so we must discuss them as a unit here) are not opposites.
The opposite of individualism is conformism. The opposite of cooperationism is competitivism, the opposite of collectivism is social isolationism, the opposite of communism is capitalism, and the opposites of communalism and communitarianism depend on what you're using the words communalism and communitarianism to mean. (They both have multiple definitions currently in use.)
Although this should be a painfully obvious fact to anyone who thinks critically about pitting individualism and any of these other five things against each other, this is not an agreed-upon point in modern Western discourse. As a child, I was indoctrinated to believe that these "two" things were opposed to one another. Even Wikipedia, which I generally trust to be relatively unbiased due to its community-edited nature, pits collectivism and individualism against each other and positions communitarianism as the direct opposite of individualism.
Proponents of capitalism, especially (in my experience) within the American education system, often tie individualism to capitalism, lying to children that you cannot have individualism without capitalist economics. This is simply and blatantly untrue. This should be a point that gets stressed more often than it does in contemporary writings and debate.
Me personally, I don't think people should be pressured to conform or to be unique, I want to build an economic system that values cooperation over competition, I think there's a healthy balance between prioritizing social bonds and prioritizing the needs of the self, I am opposed to capitalism, I think Bookchin's communalism is too statelike, and I feel unqualified to give an opinion on communitarianism because it is so poorly defined.
So, go forth and crush this myth.