They'll complain.. threaten lawsuits, demand things they don't earn, then sue you. Oh yes they will.
They'll demotivate your good people.
They'll trash you online anonymously.
They'll make you look bad. They'll lose your customers.
They'll steal.
They'll use their pay to degrade society by financially contributing to abhorrent causes and people through their purchases.
MAKE. THE. MOTHERFUCKERS. SUFFER. Eliminate their influence by degrading their lives
Just say you found someone else or are still interviewing. You don't owe them SHIT.
Hell, you don't even need to contact them. Just ignore the motherfuckers
I've had a liberal boss just get rid of me with no explanation only to post a job ad a month later to replace me. I saved the guy tens of thousands of dollars on existing hardware and more on future hardware.
Kept my improvements and replaced me with someone out of college willing to work for nothing.
Made sure to screw me in references too so I can't get to the same level work in the future.
It's a war.
File complaints against your former bosses business. Non OSHA compliance would be a good start. Any fire safety hazards will get him in trouble and if it goes unaddressed, the fire marshal will fine him each day of the violations. If you remember any illegal practices he did, report on those too.
When I got there all his systems were on fire and breaking down. I left with him having overloaded servers by 200%. He is pretty good at setting his own house on fire. I also built tools that allows you to do it easier but requires you to carefully manage the servers. Hes gonna collapse on his own.