Simple solution, Ulster Socialist. Wait for them to use violence once, just once, and then come down on them like a ton of bricks. That gets antifa the moral high ground, and avoids the stigma associated with the pre-emptive strike.
The only problem with this, I guess, is that they might not use violence, but that is highly unlikely due to the fact that fascists are by nature thugs.
"If the workers of the world want to win, all they have to do is recognize their own solidarity. They have nothing to do but fold their arms and the world will stop. The workers are more powerful with their hands in their pockets than all the property of the capitalists."
-Joseph Ettor, on the general strike
"I can get up here and shout 'I'm a Communist,' and everybody'll shrug and say 'Aw, he's crazy.' You try doing that on the outside and they'll arrest you. Why, this is the last place in America that's truly free."
-Woody Guthrie, upon being committed to a mental hospital
"When we choose between communism and anarchism we choose between Tweedledum and Tweedledee."
-Me, on the tragedy of leftist splintering