There are 2 major points here:

1. How do you believe it's possible to end the state without ending class struggle? Alternatively, how do you end class struggle globally overnight? One of these two must be possible to even begin speaking of a stateless, immediate communism. Socialist states in real life, as well as attempts at anarchism, have both affirmed the Marxist position thus far.

2. Why do you believe the working classes controlling the state will inevitably harm the working classes, just because it has the capacity for violence? Experience has shown that this isn't the case, and instead dramatic uplifting of working class life metrics has happened.

I don't really see how you can either speedrun class struggle or believe a class will work against itself when running the state in its own interests.

and violence cannot be controlled

Complete pacifism isn't really compatible with being a communist

violence cannot be controlled. It will inevitably harm the working class, even with the best of intentions.

This is an Animal Farm fairy tale liberalism tells us, and there's a very good short essay about it: https://redsails.org/the-swerve/

How exactly do you expect a country of any significant size to effectively enact communism without anything resembling a state apparatus?