How can I keep my 401k and my pension without her taking half?

We would first need to examine what portion of the retirement accounts are community. The community interest is then divided between the two spouses. It is possible for your to be awarded your retirement accounts by agreement, or by a buy-out, or by assigning other assets to the other spouse or by your being assigned additional debt to offset.

You can off set their value with some other asset. Otherwise she is entitled to one half of all assets acquired during marriage.