Individuals who are critical of people’s lifestyles or choices are usually so in order to give themselves the opportunity to impose a sense of power and dominion (over others). These acts of judgement give them a sense of grandiosity by ridiculing our choices and behaviors.
What you should realize is that these acts of judgement are necessary for them, as necessary as breathing. It is a major sign of insecurity from their end and the feelings of unworthiness and shame that are buried deep in their psyche.
I think the healthiest way for us to respond is to feel sorry for them, and, just as you proposed, to not judge others’ choices and lifestyles. You should be proud of yourself for its obvious that your are an empathetic and confident person.