I agree with telling her about a personality change beforehand. My advice is talk. A lot. Before, during, and after. If you can, setup a therapist appointment to go to together so you can have a third party help you navigate the process and communicate your feelings about it in the best way possible.
And, if it is awkward or she feels uncomfortable, give her time and don't get bent out of shape about it. You have to let have her feelings and don't invalidate them. Us spouses have to work through things on our own time and sometimes our initial reactions are not reflective of how we will feel forever.
Good luck!