An attorney should be able to answer your questions.  If you don't have
one maybe you should schedule a consultation.  Some don't charge for the
first one.  Some states view any actions (within reason) prior to filing
as 'an old, married couple fighting' so maybe you could come up with some
ideas.
 
It's legal to tape a telephone conversation in some states as long as
one party consents.  Your spouse might make more threats during a
conversation or talk about hurting them in the past.  Getting them on
tape in-person (if the situation) might work as a 'bargaining chip'
even if it wouldn't hold up in court.  I don't know if by phone verses
in-person makes a difference.
 
I've been told it's up to the judge when two parties can't agree.  Maybe
if you can prove you are the main provider and caregiver the judge will
decide in your favor, especially if your spouse can't care for them.
Find a vet that will put in writing that they should not be separated
for health reasons.  Did you have to take the injured ferrets to a vet?
If so, did you tell the vet or tec what happened?  If so, ask them to
document the reason for the visit, any treatment, etc.  in writing.
Did anyone else hear the threats being made?  Maybe you can 'trade' the
ferrets for something your spouse wants that would have to be split
between the two of you or sold.  Just be sure and get any agreement in
writing.  Again, consutling with an attorney would be your best bet.
 
Good luck and please don't let this person near the ferrets.  You never
know when someone will make good on a threat and you know what they say
about hindsight.
 
[SF]
[Posted in FML issue 5093]