What will you get out of it?
If it’s less than 3 G’s, then check to see if you can do it on your own. LV has paperwork for almost everything you want to do, legally, and if you can’t find it through the county, check online with the Bar Association of CA.
I don’t know what they are listed under, but there should be a place where you can get the paperwork and “do it yourself.” It’s cheap, but it’s often the best course to take.
Ask the county clerk’s office if they have a packet for suing your partner. That would be the place to start.
Hopefully, 100Gs plus....he owes me way more than that though.