Keep your Dignity, Poise and Grace.
What I mean is, IF they actually confront you, be so very mild and calm.
Remember "LESS is MORE". By this I mean, that the LESS you say, the MORE effective you will be.
State this line calmly "Please respect appropriate boundaries. Have a nice day" - and walk away.
Say no more. If they try and push for more, just repeat that same mild line again.
Also, remember the wise advice many have shared on this forum "The best revenge is to live a happy and successful life"
And "the only power they have over you is that which you allow"