I am mostly over cowdude now and am in good spirits. As some of you pointed out, deep down I wasn't all that serious about him either. I liked him and enjoyed his company, but in retrospect I was the one who was putting in most of the effort in keeping things going. That should've been a red flag right there. But it was sort of comfortable and non-threatening, and I let it progress instead of being more proactive.
He did email me back as I was taking the train back from Missy's. He had a knack for catching me in transit. He didn't really say anything new, except apologize and that he had told me as soon as he could, and that he had disappointed several other friends/family members during this time. It did help me gain closure to know how completely fucked up he acted to everyone and that this was not just some messed up breakup strategy directed at me. After a few days, I emailed him back and told him that it was a relief to have closure and not to wonder anymore, and wished him well. I do not think I will ever see or hear from him again.
I wish that it had ended in a more normal way, and I wish I had been more proactive all along, but at the end of the day I am sort of glad that I took the moral high road when I could've easily and rightfully ripped him a new asshole.
At this point, all I can do is learn from it and move on. I'm going to try to be more proactive and true to my inner honey badger. I'm also going to trust all of my intuitions more, not just some of them.