Is this a school gate issue? I'm familiar with this scenario if it is.
Never ever respond to her texts in the evening.
Keep being polite, friendly in a neutral way and don't rise to her baiting comments about your children's clothes or anything.
Always smile and say hello but don't engage in further conversation with her. If you find you're alone with her, let her talk and give neutral answers.
Seek out other people to talk to, never seek her out.
All I'm recommending is that you do not give her any ammo with which to attack you - stay neutral, vaguely friendly but no space for engaging further.
She is someone with issues. You will only come off badly because she is quite badly behaved. If you keep your distance and maintain moral high ground by being civil and neutral, she cannot accuse you of anything in terms of bad behaviour.
IF she ever does accuse you, face to face, (remember don't answer texts or emails - you meant to but so busy at the moment, sorry), then just say, "Don't be silly," and walk away.
This woman is not your friend and never will be.