You are right. Federal spending had been going wild.
By 1860, public debt had more than doubled in 4 years because spending was exceding revenue.
As you know, the government began borrowing large amounts of money to meet its obligations, and had incurred a great deal debt just prior to the secession of the Southern states.
Lenders were charging very high interest rates, and requiring the government to pledge public land as collateral.
With nothing to export to finance imports for tariff revenue generation, the Lincoln government was in a bad fix.
With nothing to export to finance imports for tariff revenue generation, the Lincoln government was in a bad fix. And yet with all those exports the economy of the south was the disaster area, not the North. And following the war, with the southern egricultural industry in tatters, the Northern economy didn't collapse...or even stagger. Intersting.
From
Financial History of the United States, Davis Rich Dewey, 1922, Part 1, § 115, p. 267,:
TOTAL RECEIPTS/EXPENDITURES
1854.... 73,800,000.... 55,038,000
1855.... 65,350,000.... 58,630,000
1856.... 74,056,000.... 68,726,000
1857.... 68,905,000.... 67,634,000
1858.... 46,655,000.... 73,982,000
1859.... 52,777,000.... 68,993,000
1860.... 56,054,000.... 63,201,000
1861.... 41,476,000.... 66,650,000
It does not appear that spending went wild, but rather, in an economic depression receipts declined significantly and spending continued as if the income were still there.