I'm so sorry to hear about Boo's passing Medusa. Can you separate your fighting felines in two different rooms for the day to give you some peace of mind whilst out (or two separate cages so they can see/communicate) then go thru the reintroduction ritual as with new additions to household, when you come home and have some time to give to this over the weekend?

It is so hard watching our pets grieve, it really deepens our own grieving. Chin up Medusa my thoughts are with you.