My son was called a n#$%^ by a football player from opposing school and started a fight because of it. The coach proceeded to the school blog and said it was reverse racism for him to be angry and because he was not alive during civil rights movement he had no right to be. He doesn't make his elders proud and shames black people.
Based on your question, it appears that you are talking about a teacher at a school other than the one your son attends. Assuming that is the case, if the school is in the same school district as yours you can file a grievance pursuant to policy FNG of the school district's board of trustees. Since this is a race issue, you may also contact the Office of Civil Rights at the US Department of Education. You can also file a report with the Texas Education Agency. Other than that, at this moment there is not anything else you can. If the situation persists, then you may want to talk to a lawyer about invasion of privacy and possible cyber-crimes.
This is general information and should not be construed as legal advice. Without knowing the specifics of your situation and engaging in an attorney-client relationship I am unable to provide specific direction.