EX has visits with DD about every other week (although he has been canceling so often that she has only seen him twice since the beginning of the year). Today, he had visitation from 10 to 3. I changed DD at 9 and packed her diaper bag with wipes, 4 diapers, a snack, etc. When she was dropped off at 3:45 (45 minutes late, with some notice from him that they would be late), DD was unusually upset, crying and yelling. I notice that she was very hungry and her diaper was completely soaked, to the point that her pants and dress were wet and she had a rash. Once I got her into clean, dry clothes and gave her a snack, she calmed down.
I sent a text message to EX saying that she was wet with urine when she was brought back and mentioned that she needed to be changed every 2-3 hours during visits. He responded with a text message insisting that he took her to the potty three times and she didn't pee any of those times and so must have peed on the drive back. I told him that she was so soaked and needed new diapers even in that case, because toddlers can't hold their bladders for five hours and she must have peed before then. Then, EX called me repeatedly and left a message saying that I was being disrespectful in a way that was not beneficial to DD and that he needed an apology from me for communication to continue.
So, I'm trying to figure out what to do. I know that DD's diaper was completely soaked and her pants and dress were wet. I told him this, not in a "you are being neglectful" sense but in a "for future reference, it's better to err on more changes" sense. Because of the past character of the relationship (emotional abuse, controlling behavior, and gaslighting), I feel ok with apologizing that he's upset and that there was a miscommunication, but I don't feel it's right to apologize to him for telling him that DD was wet. Input? Should I capitulate for the sake of more peaceful interactions in the future?