Help Milo pee again properly

Milo is 3 and is one of my two Christmas presents from 2016, along with Maddie, his counterpart.  Recently Milo began hiding under the bed and occasionally meowing very loudly.   Alarmed, I took Milo to the emergency vet last night, and it turns out he isn't passing his urine properly.  It's "crytalized".  They put him on IV fluids and a catheter to drain his bladder, which was FULL, and it looks like he will eventually be OK and he can come home from the vet as early as tomorrow.

I've already spent $700 on emergency vet fees and there will be more before I can bring him home.   I don't have a grand totally yet but I am estimating $1500, just based on how much I've had to spend so far.

Milo and Maddie are probably my most prized possessions.  I cant imagine one without the other, and any small contribution you could make to Milo's recovery would make both myself and Maddie very very Happy This Christmas.