communism is pretty much the exact opposite of a dictatorship
Too bad nobody told that to Marx and Engels. They teach that dictatorship (of the proletariat) is a necessary, unavoidable step in the transition to communism. In their opinion, only this dictatorship provides the force needed to violently expropriate the owners of the means of production - and therefore, it's a good thing. Engels even admired the Paris Commune, which he saw as a real life example of a dictatorship of the proletariat - and we know how well the Paris Commune worked out, and we know its human cost.
You may try the "no true Scotsman" gambit again, and say that this type of dictatorship isn't real dictatorship. But in truth, that's what it is. It's not really "of the proletariat", except in name. The real dictators are the various leaders, and Marxist theory fails to explain how they can be convinced to renounce their power after the goal of expropriating the means of production is complete. Instead, those dictators will keep the power to themselves, and use it for their own purposes. This is what happened in real life again and again. All communist countries that ever existed have gone through the step of dictatorship (more or less of the proletariat). None of them have exited this state to evolve towards full-fledged real communism. Either the dictatorship continues to this day (China, North Korea), or the system was completely overthrown (Eastern Europe, Russia - and as we can see in the later case, the communism system being overthrown doesn't mean the society becomes democratic).
The point of all this is that, contrary to your affirmation, communism is not the opposite of dictatorship. The opposite is true: communism is born from dictatorship and ends in dictatorship. That is the "real" communism - the only communism that has yet been seen anywhere, and IMO the only one that can exist, given its premises and human nature.