My question involves an injury that occurred in the state of: california

My question involves a traffic accident in the State of: California
I parked in the single lane driveway in the school to pick my kids. Another car tried to overtake me and I opened my drivers end door and hit into the passenger side of the other car. No injuries but my insurance adjusted concluded that it was our responsibility. He told me that once we park, we do not have the right of way.
I think it was a single lane parking (in a SCHOOL environment). Typically cars wait behind the parked car till the first car exits.

Any suggestions of what I can do.