The date of signing the collaboration agreement could be used to determine the date of separation. A collaborative divorce is a divorce no matter what adjectives are used to describe it. Settlement negotiations are considered privileged communications in Florida and as such are not admissible as evidence.
The opinion of the above attorney does NOT constitute legal advice and should in no way be relied upon as such. Prior to making any decision in any legal proceeding you should DIRECTLY consult and retain an attorney. Furthermore, you should verify the credentials of any attorney that you ultimately retain.
The cases I have heard stories on using the collaborative process have not been good ones. I think it is frequently used as a tool of control by one party over the other; it probably works best in extremely complicated cases where experts are needed for the children and for financial issues.