Out of sheer spite, I took advantage of the early payoff and paid it off as early as possible to deprive them of as much interest as possible

As a general FYI for anyone who reads this comment, be aware that bank loans front load the payment of the interest, and the payment of the principal is done on the back end.

So you have to pay off a loan very quickly to avoid the majority of the interest you would pay for that loan.

Finally, if you pay extra to try to finish a loan off early, make sure any extra amount you pay is marked as “principal only”. Banks are supposed to always apply any extra to the principal, but a lot of times they apply the extra to the interest, unless you explicitly tell them not to.