Is there no possible way to keep this person from texting my pre-paid verizon phone? Or do I need to just change my number?
Prepaid plans don't have the option to block phone numbers. You will have to change your number or switch to a postpaid account. With postpaid accounts, you can block up to five numbers for 90 days for free with infinite (manually applied) renewals of the block every 90 days.