PD, I'm sorry that it didn't work out and that you had to go through this rollercoaster ride. I can understand that this would result in you having a bad association with poly. I tell people that just because someone is poly doesn't mean they automatically know how to do good, healthy relationships - and it sounds like he might have been a bad example, at least in this context.
I am glad that the experience opened up some preconceived ideas that you had and I hope that, once the pain and grieving has subsided, you will see some positives that have come out of this.
I wish you luck.
"Listen, or your tongue will make you deaf." - Native American Proverb