If you registered it with the California Secretary of State's office, then you will need to file a Dissolution of Registered Domestic Partnership. The Secretary of State's office would have a record of the Registration, if one was filed. If one was not filed there, then you are not considered Domestic Partners under the laws of California.
However, to my recollection, you could only begin registering with the Secretary of State's office in 2003.
If you are RDP's, then you are treated the same as married couples in the State of California. Therefore, you must divide community property and deal with spousal support, etc. However, no community property would be created after the date of separation (only from date of Registration to the dated of separation). Furthermore, considering the length of the Registration (if any) and the time since separation, I seriously doubt anyone will receive a spousal support order.
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