Hope, do you feel comfortable and confident discussing the issue in person? One of the wonderful benefits of no longer being in a relationship is that you aren’t required to work things out, or communicate, or even ask the other person to do anything. You aren’t required to sit there and hear his excuses or justifications if you don’t want to. This doesn’t make you a bad coparent.
As long as your daughter is safe and content, does this issue need to be raked over the coals? If what he did sets a precedent you aren’t okay with, you can calmly and rationally state your case in writing so you aren’t exposed to his emotional reaction. I fear that you will end up hurt and disappointed again by continuing to engage with a man who cannot or will not meet your expectations for successful coparenting.
Just as an aside - a person who is capable of deceiving and betraying their primary relationship in life can’t be expected to act with honour or integrity in other areas of their life. Not to say they can’t do it, because I’m sure some do, just that it should surprise you if they don’t. It’s like being surprised that a murderer is okay with shoplifting.
I know that I stopped feeling upset when I stopped caring what XH does with S2 on his time. I can’t control it, I can’t dictate it, I can’t even have expectations for it. I haven’t asked about it in many months. As long as S2 is returned to me in good condition, I consider the visit a success. I know (guess?) you are still aiming for reconciliation though, while I am running eagerly towards divorce, and my XH is one of the worst on here by the sounds of it.
Parallel parenting is working well for me. His and hers parenting time. It doesn’t seem like something you’d want right now, but it’s an option if you are struggling with detachment. Are you coparenting under the guise of perpetuating and reviving the marital relationship? Maybe ask yourself why it’s so important to you to have a successful coparenting relationship. Is it for your daughter’s sake or yours? Is it a fear of failure or fear of letting go?