I left a job 8 months ago. Another ex-colleague finally got sacked 6 months ago. My new job is in the city centre. During the times I go to the shops during my lunch hour, I keep seeing the silly ex-colleague that made my and several colleagues' lives hell as she did do hardly any work and it was full of mistakes. She should have been sacked 15 months previously to this. Now, this ex-colleague (probably still has no job as not dressed in business clothing) tries to approach me or looks me in an awkward manner. I have nothing to say to her as it's her fault for getting the sack. I always say to her 'got 5 minutes left of my lunch break' then storm off (most of the time I am lying). This really annoys me that she is doing this in such a manner to say I am in the wrong, well in fact it is her. I have texted my other colleagues at my old job. She is doing the same things to them as she does to them. What do I need to do if she approaches me again?