You're a licensed marriage and family therapist. You're treating an unstable client. Do I really have to say it?
Don't have sex with her. Not once. And definitely not for 16 months.
Human interactions are complicated. Plus, things are often more complex than they appear. There are also difficult-to-explain equities and particulars of any given relationship.
Still. Just don't do it.
Even if you win -- temporarily or permanently -- in the Court of Appeal, as here, it's still not worth it. By a longshot.
And I'm quite confident that even Gary Ventimiglia, the petitioner here, would agree.