Legal Question in Criminal Law in California

The facts you describe do not amount to a crime. Depending on the circumstances, though, it might look like you and your friend are doing more than you claim. (Your comment about "real proof" suggests there is at least some basis for the mother's beliefs.) If that's so, the authorities may very well investigate. Actual charges seem unlikely, but then I don't know what the evidence will show.

Whether you claim no sexual conduct or not, a parent can try to bring various criminal charges, not limited to sexual relations, and might succeed. That doesn't mean you could be convicted, but it would create serious problems for you. The laws are intended to protect minors from adults, you. Parents are the ones who file criminal charges when they think their children are in danger. Choose wisely.