There is some wisdom in what you are saying but it wasn’t that the South was so in love with slavery. Many Southerners including Lee were opposed to slavery.
The reason so many remained defiant is because any time someone from the outside demands that you do something and attack you, you become defensive.
The fact that the worst of the abolitionists were the same states which were heavily involved in the slave trade when it was economically beneficial didn’t help.
And the truth is most Southerners really did believe in local and states rights. They were extremely wary of a strong Federal government.
This is, of course, why they demanded the passage of the 1850 Fugitive Slave Act, specifically intended to override state laws making return of fugitives to slavery more difficult.
The specific issue over which the Democratic Party fell apart in 1860 was southern insistence on a federal Slave Code using federal power to force slavery on occupants of territories against their will. When northern Democrats balked, southern Democrats split their party three ways, handing Lincoln the election.
IOW, southerners didn't dislike federal power at all as long as they controlled it, which they did for most of the period from independence to the WBTS. In fact, in at least those two cases they demanded significant expansion of federal power.