Figuring out what portion of my rental income comes from the ICE client is not possible, as the family member who manages it declines to go to the trouble, which I understand is considerable.

The obvious response of "talk to your family member and figure out what the actual facts are" somehow never comes up.

Someone else highlighted that various types of funds (including pension funds) are often invested in similarly dicey business. This is a great place to educate and agitate, because a lot of people would be similarly troubled by this investment, but you actually have to talk to someone and probably do some digging.

You can’t unilaterally break the lease.Even if you could, ICE would simply relocate its facility.

You can usually break a lease if the tenant is doing something illegal on the property. Force them to fight an eviction. Force them to go to the trouble of moving.