It sounds like you realize that you want the fantasy back. And that's all it ever really was, a fantasy. I highly suspect if you look back, you've been making excuses and rationalizations for his behavior for a long time just to hold on to that fantasy.

Put it in perspective, you really don't care what this man thinks/feels/does. But this fantasy man that you've created in your mind will cause you pain for as long as you allow him to. Granted your feelings are real, but the relationship was not. I try very hard to look for the silver lining these days, your silver lining in my view is that his behavior has popped that fantasy bubble and given you the opportunity to really address the underlying problem. As I've stated before, until you address the source of your unhappiness, the real source, you're easy prey for the next guy that sees you're vulnerable and says what you want to hear.

I am in no way trying to belittle the feeling of betrayal and all that goes along with it. It cuts us to the core when people treat us like garbage. BUT it's a cliche but I'm a firm believer you reap what you sow. Right now you're planting garbage and it's time to change your supplier.

Think for a few minutes about how things would have been differently had this been Mr. Right. Certainly if he had genuine feelings for you and your well-being he would never have tolerated having only a sliver of your life, it wouldn't have been enough. And if he had really been all you thought he was you wouldn't have been satisfied with a part-time relationship either.

Now you get to decide where you go from here.