My only suggestion is to not validate his time with OW by wishing him happiness with her. It sounds like you didn't mean to. I'd suggest maybe just flat out ignoring her in conversation and only talk about him next time.
I'm glad you feel more peaceful. I know you've really been on a rollercoaster lately.
Yes. I regret it greatly. It makes it sound like it's o.k. Like he can do what he wants and I'll be here waiting. I can't imagine why I said that! Well. If that's what he thinks, he's wrong.
I'm riding the gentle hills of the straight away now. Slight blips here and there throughout the day since H left. But not too bad.