So I realized this session was a wash. So I told my d. I love her very much and I am very sorry you had to witness that. I said I know you are upset right now and you don’t have to stay. She looked at me shocked, and replied really? I said, yeah babydoll you can go if you want to. She said thank you and got up and walked out.
This part you did right. You acknowledged her feelings and you showed your caring for her. You put her needs ahead of your own. You showed that you were the calmer, steadier parent (although it would have been better not to engage with your ex at all) and your ex will look bad by comparison - mom creates a scene in front of the therapist, dad is calm and acknowledges daughter's discomfort.
No guarantees - she might have just been happy to get out of the session - but if you're lucky, this episode of seeing the two of you contrasted together might just start to plant the seed in her mind that you're not the bad guy mom makes you out to be.