It is not a thing which cannot be corrected. For now he or she needs healp. If your institutional policy allows give her medical leave and take her back once she has overcome the problem with the help of treatment.
I would agree with JThomp42. Also, having a recovering staff person available to help with a therapeutic intervention will lessen some of the shame, guilt or fears that the nurse may have. Inquire online for Impaired Professional groups to facilitate this. (I have been in recovery for more than 25 years and ran a women's facility for more than 20 - about 20% of the population were in the medical field and ultimately returned; better equipped and there to help other professionals recover.)