Based on previous experience, I'm going to guess that the $36000 "bill" is actually a recoupment of SRB payment(s).
Each contract contains language that spells out that your any/all of your paid bonus may be recouped if you fail to fulfill the terms of the contract, i.e. maintain yourself within the fitness standards, get de-nuked for poor performance or drugs, etc.. IF you are discharged due to medical problems, that historically would not have triggered the recoupment process, unless the medical condition was in some way self-inflicted or self-created.
Additionally, if you were being treated for depression, previous policy made this a disqualifying condition for service in the Nuclear field. Things may have changed in the 3 1/2 years since I retired, but I'm sorta skeptical of that.
I'm also going to point out the obvious; there is FAR more to this scenario than what the OP has told us or ever will tell us.