The analysis of a sentence

The sorceress Jasra and her son Rinalod are the protagonist's past enemies and present allies.
The protagonist is talking to Jasra about equations.
The protagonist took Coral, a daughter of the prime minister of Begman, to the Pattern, which is a maze-like sanctuary.
She believed she is a daugher of gradnfather of the protagonist and put her foot on the Pattern; goint turough the
Pattern give one several power but non-royalty-of-Amber must be killed by the Pattern, or even the royalty can be killed by a mistake in going through.

"At any rate, once one begins the Pattern, one may not turn back. I was obliged to instruct her as she went along. That, or be a very poor host and doubtless damage Begman-Amber relations."
"And spoil all sorts of delicate negotiations?" she asked, half-seriously.
["Knight of Shadows" of The Great Book of Amber by Roger Zelazny]
I'd like to know if the underlined sentence means the following.
"I must do that, or I would have been a very poor host and done doubtless damge Begman-Amber relations."
Thank you in advance for your help.