@Daniel415
The host is clearly not in a good mental state to be accepting guests into their home at this moment in time. Whatever his/her problems are, they need to be addressed, and the host needs some help and support, something, that is way and above the need for having the odd guests in for the weekend.
You could contact the local Police,or even local hospital who have contact to local support organisations who could then call on the host to check on them and ask if they can be of any assistance/support. These organisations are obviously experienced in these matters and can provide the support that this host might need.
You could check the calendar for the host property and see what the bookings are like ..i,e frequent future bookings or not another for a while....?.. a number of upcoming reservations may well be too much for the host anyway.
The host clearly needs someone to talk to.
You could write a private message to the host and say that during the weekend you were both concerned for the hosts well-being, and whilst the property was nice (and all that) you did not feel comfortable due to the difficult,personal circumstances that the host is now having to deal with, and suggest that he/she take time to consider taking a break from hosting in order to put priority to their own well being...and obviously wish him/her well.
The co-host may not have a close connection to the host but they maybe in a position to contact a family member/friend who can assist and provide some support to the host.
I think the priority is the host well being and the suspension of any further guests for the time being. "Dragging the co-host" in...is a non issue. I am sure they would support the priorities here
On your review I would be fair about the property,provision etc, but write a diplomatic short paragraph that suggests that the host was heavily preoccupied (with personal issues) and not able to be very attentative (or words to that effect) and leave it for the reader to interpret.
There is also a space at the end of the review for you to inform anything about the host to AirBnb. In that box I would write your concerns and suggest the host is suspended temporarily.
I guess I am just thinking out loud and offering some suggestions. I would see what other hosts suggest too, to get a balance of different opinions on the issue