I have sheet metal confusion - can you help?

Hi all -

I have a sheet metal part - a flat strip with its end rolled into a conical section.  I have attached it here.

The flat pattern does not work - and maybe that's ok.  I just hate sending files with errors to a vendor.

In my assembly, after the conical section is formed, the end needs to be trimmed to fit an adjacent part.  I am using a plane to make this cut - but the cut is not normal to the sheet.

I have tried many ways to get the cut to be normal and have not found a perfect solution.  But I stumbled on something and wonder if this is normal, acceptable for fabrication, and the intended use of the feature...

It seems strange to me, but maybe it is intended functionality:

I make the cut which produces a non-normal edge to the sheet.  (see the image below) Then I unbend and re-bend and the edge is apparently normal to the sheet.  It looks great, but the flat pattern still fails.  I am thinking that a shop can suppress the re-bend and get the flat geom they need and we will all live with a failed Flat-Pattern at the end of the tree.  For ever and ever, amen.

That sounds hoky to me, but as long as I get my parts made right...

I am attaching the sldprt (2015) - is there a better way to model this thing?

Thanks!

-Nate