Bonded pair and loss...

Hello all.  I haven't posted in a long time as life has been great with my two male quakers. Boncuk, 7, and Zaza, 6.   Three years ago they became a bonded pair -- in every sense of the word. They even moved from their separate cages to an empty cage I had in the room, and constantly try to build a nest from reading glasses. Amazing stuff. Two days ago though, Zaza broke his leg in a bad spot - above the joint.  Three weeks ago he broke his wing. My vet xrayed him on Monday and the wing is healing, thankfully. She noticed many irregularities in his xray -- bones not light and hollow like they should be, uneven air sacs.  He has lost weight and his poop shows liver trouble. She believes there is a systemic pathology in Zaza, and doesn't want to stress him more by drawing blood at this point.  While under anesthesia we considered euthanasia, but then decided on giving the leg a change to heal and keeping him medicated and quiet in a tiny carrier cage. Will re-xray in 2 weeks.  The trouble is his buddy - Boncuk has been literally by his side 24/7.  I had Za in a fish tank, and Boncuk insisted on joining him. When I move Za to a small carrier, Boncuk sits on top.  I am sick with worry about this situation -- I feel that chances are good that Zaza is not going to make it -- what do I do about the loss with his partner? I have three other larger birds, but they don't interact with the little ones much. Advice appreciated -- will the "widower" be ok? I don't really want to get another parrot at this point, but will I have to?  What do I look for in terms of trouble with the remaining bird? Thanks for reading this long post and replying if you can...