Private User -- can you be real specific? It is not obvious to an 'outsider' what needs to be done ... and, as a Pro member, you should be able to do pretty much everything that needs to be done.
The key is that there is no 'un-merge' capability at this time. You just have to re-create your private profile for her. Then, move your proper spouse and relatives to your new profile. After you have 'connected', for example, her partner, then edit the Relationship in the partner's profile and disconnect the other spouse (you may want to make the names slightly different initially in order to tell which is which, then rename afterwards). You do the same for each child who needs to be reconnected to the proper parents (again, make sure the names are different so you can tell them apart).
If you run into a 'disconnect' that doesn't work for you, then a curator can help if you make the profile public (long enough to get 'fixed'); you can make it private afterwards. Unless there is a curator in your Family Group who can help (in which case you don't need to make them temporarily public).
It is a pain to unmerge --- because it is really just a 're-create and move' operation. Most of us have "been there".