[2020] Accidentially travelled to New York in a Co-Op session and my mate doesn't have the DLC

Hi,

I accidentially travelled to NY in a coop session and my mate didn't have the extension. We sunk 20 hours into this game and I'm not starting from scratch. I only have this DLC because of Uplay+ and I don't want to play alone from now on. We started this game together and want to finish it together.

I found some threads mentioning a hint that you cannot travel back once you travelled there. I didn't notice it. Are they f*cking serious? This would ultimately end the game for both of us :-(

Kind regards,