How to disclose med error/write up to hiring manager (internal position)

I shadowed in the ED today at a hospital affiliated w/the outpatient group I work for.

I had applied/interviewed//shadowed/been unoffically offered a position by the manager about 1.5 yrs ago, but I hadn't been at my current position 6 mo, so per HR I was not allowed to transfer

I just reached out to the manager again, did the shadow, and will tell her tomorrow that I'm interested. She told me today that she would like to hire me if I'm interested

About 6 mo ago, at my outpatient position (affiliated w the hospital/same HR) I made a medication error and got formally written up. No harm came to the pt but it was a pretty big error in the sense that I gave her 4x the amt of medication (it was an IM steroid).

4 months prior to that, I had followed a drs order to administer a medication that is given every 6 mo for osteoporosis. We had just switched to EPic. THe dr told me the pt had never had the med before, the medical assistant said pt never had it, PT said that she had never had it, and her husband confirmed this as well. There were no prior admin's on the q 6 month order.

After I gave it to her and was looking through her chart, I found out the pt had received it 3 mo prior-- everyone involved had just forgotten, and due to it being admin'd off a separate 1x order and the switched to the new system, no one caught it. I filed a safety report.

Because of this incident, I was written up for the 2nd one *and* they included this one in it as well.

So I am pretty sure (i will confirm w HR tomorrow) that the HR person who will be involved in applying for the ED position will be able to see this in my record.

What is the best way to bring it up? I feel I should tell the manager directly so she doesn't hear it from HR. I have learned a lot from the mistake, am much more careful/present during med administrations, am very strict about following correct procedures, double/triple check everything, etc. I am thinking of putting it in my email to her tomorrow when I let her know how shadowing went (although maybe I shouldnt put it in email?)

Any tips on how to present it?

I am worried she may not want to hire me when she finds out, which I know I cant change, but I want to present it the best way possible