But the Southern states abrogated responsibility for their share fo the debt, repudiated treaties, stole what they wanted and threatened the central U.S.
This is disingenuous, at best. Surely you are aware that one of the Confederate government's first acts, in March 1861, was to send three peace commissioners, headed by John A. Campbell, to Washington to resolve the very issues you are accusing the Confederates of abrogating. (I also believe the commissioners carried assurances of continued free Northern access to the Gulf via the Mississippi, but I'll have to check on that). At any rate, Lincoln refused to meet with them.
Nonsense. Read the instructions the commissioners had. They were there to establish relations between the U.S. and the confederacy. Period. No talks to end secession. No offers to stop the rebellion. The only result acceptable to the delegation was acceptance of the legitimacy of their actions. Only after the U.S. had surrendered to their demands was there a vague offer to talk about 'matters and subjects interesting to both nations'.
And even if the offer to negotiate had been sincere, don't you think it was a little late? The South walks away from the debt, seizes what they want, and only then offers to compensate? Isn't that a bit like me taking your house and only then offering to pay for it? The time to settle those issues was before the South left, not after they had walked out on their responsibilities and seized what they wanted. If anything is disengenuous it's the suggestion that the South sincerely intended to pay for anything.