Can I sue my School district for Slander, harassment, defamation of character & possible bullying of a minor by adult educator?

Assistant principal told me my son for a fact was "drinking, smoking, doing drugs, and having sex" on "the Hill" by school. I have been threatened with Slander by the principal and her boss, the principal's boss also threatened to kick my son out of her school for no reason, and they have now recently almost gotten me kicked out of my apartment because they told the police that me, my student, his sister and his father were supplying drugs to the school. Now the drug dogs have been out to our place over 12 times in 3 weeks! They have tagged my cars and labeled my son in school as a druggie/drug dealer. I can sue, I am very poor, I have no money for an attorney, and legal aid said they could not help with suing cases. How can I find a pro bono lawyer to take my case? It's effecting grades.