First of all, telling spy over and over and over that you're done with H is not going to work. Methinks the lady doth protest too much... As I said before and Wholeagain said recently, don't talk about H at all to spy or anyone who will talk to H. Remember that actions speak louder than words. Only talk about good, fun things going on in your life. You can be miserable, angry, emotional, whatever, all you want when you're alone in the privacy of your own home. To the rest of the world you project confidence in your new path.
In fact, I would take it one step further and tell spy you're no longer interested in updates on H. You've accepted that he has chosen a separate life and you want to respect that. Trust me, that'll get back to H in an instant!
Detachment and no contact isn't about being a bitch. (I had that problem too.) Think about how you would interact with a neighbor or coworker. Don't be rude, just not overly friendly. Don't ignore H's questions if they aren't coming the way you want to receive them. If he's asking a valid business question then respond when you're able.
I think you were fine with texting back because you were busy at work. Then you left a message to explain that. Not sure that was totally necessary but it was fine. Next time if you just want to keep it to texting just include in the text--busy at work, can't call.
And the fact that you're all over the place now says to me that you should stick to communication you can plan. Don't overthink everything, but you should think things through instead of going on the fly until you're more settled in your emotional responses to H.
Hugs!
If you love somebody, set them free. http://tinyurl.com/2empx2g