I asked what was wrong and she said I had lied to her by not telling her the step-D was going with me to shoot pool. I didn't get angry, I just calmly said "I didn't know she was going to come until after I left", and then I laughed and asked "why would I need to lie about spending time with my kid". W sort of smirked and said "I didn't say it made sense"... This whole exchange seemed really weird. Like she was somehow jealous despite what she had done and despite her asking for an open marriage.
There may be a motive at work here. Often, cheating spouses try to bring the non-cheating spouse down to their level ("we're both liars"), similar to the way she wanted you to buy into a "hall pass". Steve85 has dealt with EAs successfully, and is a great person to have listening and commenting on your situation.
