This is really a question for the Board that licenses Social Workers.
As a lawyer, I can tell you this doesn't appear to be much of a malpractice case. First, your Mother contacted the LCSW, the Social Worker did not solicit information about you. Since she hadn't met you, it is unlikely that she revealled any confidential information to your Mother. A Social Worker could easily say that obtaining information on your family dynamics is part of the job.
Second, you did not indicate if the information could be proven to be true or untrue. It appears to be subjective opinions which a judge or jury would have a hard time seeing as harmful.
Third, you indicate few damages. Have you seen another mental health professional to evaluate if your response to this social worker caused you measurable harm? If not, the most you are likely to recover is the cost of that one visit.
In conclusion-"Anyone can sue anyone over anything." This is not likely to be a successful outcome for you. In other words, you picked a Social Worker that didn't meet your needs. Move on and find one you are comfortable with.