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I'm sorry to hear about your situation, and my condolences on your loss. Yes, you are "first in line" before any other next of kin. Here's the law that governs that: http://www.leginfo.ca.gov/cgi-bin/displaycode?section=hsc&group=07001-08000&file=7100-7117.1. Basically it says first to spouse, then to child, then to parent, then to sibling, then to further relatives (and so on...). Now you might need to file a "temporary restraining order" depending on what occurs, and might have to go through the probate court to enforce your rights. But you are "first in line" here, as you're the next of kin, and can prevent any relatives further down the line from doing this.
That being said, you need to contact an attorney in the area that deals with probate cases. Go to www.lawyers.com or www.legalmatch.com to find an attorney in your area. You should be able to find one that will give you a free initial consultation and better advise you of your rights, any problems with your case, likelihood of success, how courts are treating cases such as yours in your area, and what you should do next.
Hope that clears things up a bit. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable. Please note that I don't get any credit for the time and effort that I spent on this answer unless and until you rate it positively (3 or more stars). Look for the stars on your screen (★★★★★). Thank you, ***** ***** luck to you!