I work for a company of about 250 people in size and have been there about four years. Unfortunately I had a toxic manager for the last 18 months. She would subtly undermine me in numerous ways and it really knocked my confidence and made me feel quite anxious. Fortunately an internal role came up in another department recently and I was able to transfer. My new manager is lovely. However, I walk past my old manager in the office every now and then and she insists on saying hello, despite the fact she essentially pushed me out of my old role. AIBU just to ignore her?