Dear gajraj, If the entire lump was removed for the biopsy and the findings were negative for breast cancer, that is definitive that this lump was not breast cancer. We are not experts in the diagnosis and treatment of tuberculosis, your question may be better directed to an infectious disease physician.
It seems clear that cancer has been ruled out safely; so the slow healing is due to infection of some sort. It sounds as if TB may be the cause; having just found that out, proper treatment ought to lead to healing. But it could be slow, since TB takes a long time to be cured.