Honestly, just do your best with all other areas and move forward with confidence. This doesn't define you nor does it make you a bad candidate/future nurse, and while, yes, a program may not view the IA as a point in your favor, it's not something that will always immediately send you to the bottom of the pile. No one has a perfect application. We all have things that might not be viewed as amazing.
You can stick to programs that have an essay or interview component that allows you to address this in more detail. Show them that this mistake and how you handled it will actually make you a better nurse because you know how to own up to your mistakes and move forward in a positive way. That is a vital skill in nursing, where mistakes happen too frequently and fixing what led to any mistake can invaluable to patient safety in the future. Would you rather a nurse who makes a med error, immediately reports it, ensures patient safety, and helps determine what went wrong and how to prevent future mistakes like it or a nurse who makes a med error, is terrified of the consequences, and doesn't do anything, placing the patient in danger?
You made a mistake, you dealt with the consequences, and now you are more mature. Because of your IA, you are never going to do something like that again I'm sure, and you will make sure you do the right thing if you ever make an accidental mistake. The IA itself may not be a positive, but it did give you an opportunity to grow and become a better person. That's what you focus on in your interviews.
(And honestly, the competitiveness of an ABSN depends on the program.)