I was ... preparing to ... leave the mark to port since there was no gate. Well another f18 was coming in on starboard and intending to leave the mark to starboard as if it were the starboard gate...
This is one of the problems that occurs when Race Committee sets an unintended course. I think both boats have a good argument for rounding on opposite gybes and when that is the case, Rule 18 does not apply. RRS 18.1 states "Rule 18 applies between boats when they are required to leave a mark on the same side...". So, in the absence of Rule 18, only Rule 10 applies and it is a plain starboard/port encounter. The port boat was obligated to keep clear (which it sounds like you did), but may exonerate herself if not (which it also sounds like you did). Had you filed for redress under Rule 62.1(a), I think you would have had a good chance of receiving it.
Situations like this are why SI's should be careful not to set unusual courses, and RC should take care to set them properly.
Regards,
Eric
