I run into my students often and usually at Walmart because it close to my scool. I say hi how are you. Usually we're both passing each other so I don't stop to talk. To me it's rude if you make eye contact with someone you know but don't acknowledge them in some way, even just a smile is ok. They may not know it's hard for you but just try anyway.
You don't have to blow out my flame to make yours burn brighter.
When you judge another, you do not define them, you define yourself.
How people treat you is their karma; how you react is yours.