Like Traveller said, “I’m looking over the documents and will get back to you in a couple of weeks”.
As for being questioned if you are seeking a lawyer. It never does any good do outright lie. I’m sure she realizes how foolhardy it would be to divorce without legal counsel. In my locale without legal representation - unless the divorce is really cut and dried, like 50/50, both make the same money, etc - the courts won’t accept it and will send it back looking for more information. Both sides need to have their own lawyer to petition their divorce to the court.
Also, you will be negotiating. Lying will not be a gain for you in that endeavour.
Being vague might buy you some time. But to what end? Eventually she will learn you have a L. She will then need to get one (which she probably already will have done before all that). And she will likely see it as some breach of trust.
Be upfront and say “Yes, I am going to talk to a lawyer and I suggest you do the same”.
If she pushes and asks why. “Divorce is a complicated and unfamiliar process to me. Lawyers do this for a living, I don’t.”
D
Feelings are fleeting. Be better, not bitter. Love the person, forgive the sin.