A great many of them were treated the way the losing side in most civil conflicts were traditionally treated: imprisonment and in some cases executions, confiscation of property, disenfranchisement, etc.
About 2% of the population of the United States fled the country in the Loyalist exodus.
Which is why I find southern claims of their great mistreatment after the War so unhistorical, the fact being that the South was treated less harshly than any similar group in history after a great civil war. Exactly one trial and execution for war crimes. Not one for treason.
So...
Lets treat this like the secession from England then shall we? Or better yet... lets be a little better behaved initially.
Secession does NOT = American Civil War
Secession. In this case. Means we acknowledge the truth that there is no hope of rehabilitating the mass of people who vote for tyranny.
I know some who think its proper to suffer under tyranny if its voted for but thats just F’ing BS. There is no vote that can take place that legitimizes the tyranny we NOW suffer under and the impending escalation of that suffering. We the people DO NOT get to enslave ourselves and others as long as we vote on it. Secession, in this time, means acknowledging that there will be no reconciliation between being free and being livestock.