Questions about surviving spouse's entitlement?

Hi Guys, Here's the situation. Say husband passes away, surviving spouse is claiming a 1/3rd of the husband's estate (which he owned prior to the marriage), husband's 401k, and 1/2 of the life insurance. Kids (form former marriage) were listed as beneficiaries on the life insurance and already received the payout. There is a trust that gifts the husband's 1/2 interest in the estate to his kids, however, the title of the house was never put into the trust. Kids find out that there were legal separation docs filed 3 years into the marriage (in CA), and finds a marital status document signed and notarized by both parties that explicitly lists the estate as separate property to the husband, and also includes verbiage that waives any claim to any retirement plans, pension plans, etc. for both parties. Is the wife entitled to anything in this situation? Does the marital agreement override any community property rights the wife may have built?