I would let some of Kalifornica go. They would not get to force the republican interior to go with them. They also do not get key military installations including the key harbor in San Diego and free access to it.
After that, with one party rule, unlimited immigration from Mexico, it will not take long for Mexico to draw it into their orbit for re-unification. It is then not a long step to Venezuela status.
And, Kalifornica has to take their portion of the National Debt, and pay for a wall around what it is leaving.
I'd assume the current crop of "illegal" immigrants, who have been agitating for a 'reconquesta' would be granted citizenship in the newly formed "Mexafornia" the newly formed country sans all current US military property.
PS Good luck Governor, (president?) brown. Don't come crying to the US proper for funds. You've made your bed now sleep in it!
Regards,
GtG