I'm sorry about your wife's death. Since the house was in her name alone, you will either need to initiate a probate proceeding OR you will need to initiate a "spousal property petition" if you can explain to the Court's satisfaction why the property was only in her name even though she was married when she purchased it.
If you need assistance, I would be happy to help.
The information you obtain at this site is not, nor is it intended to be, legal advice. You should consult an attorney for individual advice regarding your own situation.
You indicate that the deed on the house states that it is your wife's separtate property. You do not state whether your wife had a will. Absent a will leaving all of her assets to you, in an intestate estate separate property is distributed differently than community property. Whether the property is really separate or part separate and part community, requires a lot more facts and is too complicated to do in this format. If there is a will leaving all to you then a petition as previously suggested is fine. But otherwise, I would suggest that you consult with competent local probate counsel before any petitions are filed with the court.
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