Cheers for the input guys.

I have some new strategies so i will reload an earlier save and provoke it after preparation.
My income did not go negative during the realm divide as I had already invested much in infrastructure but it did once one of my trade fleets was attacked by Wako (thankfully they got captured and all my ships were back in position for end of turn).

Looking at the threads I find it interesting that the realm divide penalty does not apply to vassals created after the realm divide event and I think i will use that to my advantage to "make" some friends and trading partners.

My own feelings about the event are mixed, while I do like the challenge I do think that the realm divide penalty should not hit your "Very friendly" long term allies hard enough to enter war (and should not hit vassals at all) but everyone who does not have great relations should take the big hit and side with the Shogun.

To me this would make more sense as the realm divide would be more like a civil war then with the old Shogun and his supporters vs the upcoming shogun and his supporters.

Losing all diplomacy is a real immersion killer for me with the event and I think it should be scripted better so that you keep your vassals and maybe a couple of your very faithful long standing allies vs the rest of the map (who have penalties so harsh you will never win them back), it would be more keeping with the atmosphere of the game.