Communication with ex is impossible, everything turns into a fight

Whenever I text my ex about our kids or logistics she interprets it as criticism or gets defensive. Simple question about soccer practice turns into her going off about how I never helped enough when we were together. I'm trying to use the co-parenting apps but she refuses to use them and only texts. I don't want our kids seeing us fight but at this point I'm exhausted. How do you guys manage this?