NTFS or ExFat: Security vs. simplicity? What would you do?

I'm about to format a WD Duo 4TB for use by two different windows laptops at home (mine and my spouse's)  (1 partition, my_data & spouse_data folders)

The two laptops will NOT be part of the same workgroup and there's no domain at home because I don't want my spouse (bad user) to inadvertently get infected and compromise my laptop or our shared WD backup HD.

My plan is that the drive will only be connected to each laptop when its internal SSD fills up and projects need to be off-loaded to the WD box.

I suppose one advantage of NTFS is that I could restrict access to my folder using NTFS permissions.

A concern I have (perhaps unfounded)  is that I have been able to "take ownership" of an external drive.

If I could do it, could malware?

If my windows config ever got messed up, would I lose my security identifier?  (I guess that's not a big deal, I could just take ownership, delete the old identifier and apply the new permissions to all sub folders).  There won't be any fancy security, just permission for each user to the appropriate data folder).

If I just go with ExFat, will I make my life simpler at the expense of security?

Any tips or thoughts before I format the drive and copy over the data?

Thanks,
Mike

PS: As I finished typing this question, I think I just talked myself into NTFS but wanted your input.