Weeble, I think you were fine. Frankly, if this woman thinks that no wanting to see an exposed male posterior in public makes you immature (her "grow up" comment) what does she think verbally assaulting someone in the grocery aisle constitutes?
Exactly. I don't think it matters how shocked WW's mom's expression might have been, she had an immediate gut reaction and then kept walking. She didn't stop and stare, point, comment, etc. The other woman, however, decided to rant and curse. She also could have had an immediate gut reaction (being offended that two strangers were offended at her husband's bum), composed herself and moved on but she chose not to. I also don't think WW's reply to being cursed at was unreasonable. Maybe she should have ignored it, but she also could have cursed back. She didn't. It's okay to defend yourself even if you don't have
IMO CursingLady is at fault for the entire interaction.