I'm glad the will issue has been clarified, all you have to do is get your share, the value of the estate should be declared at probate, just take her to court to get your share. Because a lot of the value is likely tied up in the house, it may have to be sold which she will not like one bit.
Mirror Wills
Are entirely appropriate for young couples, you have no idea what the financial position will be in 20 40 or 60 yrs time. On the first death the surviving spouse gets the lot TAX FREE. They can decide what to do according to circumstances, if possible some should be distributed to any children by varying the will.
In my case, my husbands business was wound up and most of his half was shared by our daughters. My own share was the house, which I downsized, a life insurance payout and pension income, my costs are modest so when I go the house will go to the kids.
I do have a relationship with a man but I have no intention of marriage or even living with him because that would really upset the rest of the family and make them insecure.
Other women would want the security of marriage, her husbands first family will be very cautious if not hostile, however good her intentions, that hostility will make her dislike them.
ALL the second wives that I know have a poor relationship with his family even if they know that provision has been made in his will they still don't trust it.