I'm so sorry you had this experience and sorry also if I'm repeating any posts as I don't have time to read all the responses.
I have been bothered a lot sometimes by rude people at the gyms I used to frequent, although I now have a gym room in my house with all the equipment I need and that saves me time and money and I can focus without socializing (although socializing is nice), so I know how you feel.
But I had one thought that unless you actually talked to the woman and kids about it (again sorry, didn't read all the posts, maybe you did), you don't really know what they were thinking about you or whether they were thinking about you at all or whether they were thinking about you in a positive rather than a negative way.
Most people who frequent friendly gyms (there are some snooty ones out there) are either silently or vocally cheering others on who aren't at a level of fitness that maybe some other members are. Sometimes they are quietly watching the progress being made and silently supporting and rooting for progress. So it is possible the woman actually was admiring you for your spirit and work.
It's also possible she was just staring into space and thinking about her own thing.
Whatever the children were thinking, hard to say. Kids are unreadable a lot of the time.
Either way with all of them, whatever they think is totally irrelevant to who you are and what great things you are accomplishing and you can't afford to give it house room in the brain.
Huzzah! Be happy! Fitness is a joy, it matters not what anyone else thinks, this is YOUR journey.