What he is doing IS a crime: Electronic Communications harassment under California Penal Code Section 653m (b), a misdemeanor, carrying a maximum punishment of six months in jail and a $1000 fine. I suggest you send him a certified letter stating that his many contacts are unwelcome. Advise him of this penal code section and inform him that starting (estimate two days after the letter should get to him), if you receive any further contacts of any kind, you will report it to the police and have him arrested. You can also obtain a restraining order by going to court, but the former action should take care of this problem. Download the text messages and save them. Same with any emails.
If this escalates to following you or parking outside your home, call the police immediately, and get that restraining order. Good luck.