"Casual" friends are not supposed to catch feelings.

A little over a month ago I was "reunited" with an ex. Well technically he wasn't an ex because our "relationship" from 8 years ago was never really defined. Yes we slept together then, & it was of course the best we both ever had. He has spent almost the last decade telling people that. When we got back into contact we both agreed that we were at a point in our lives where we were not ready for a relationship & decided to be casual friends, or friends with benefits so to speak. We texted non stop for the first week, phone conversations as well as emails too.Reminiscing & talking about how great we were together & how we used to talk for HOURS on end. He said all the things I wanted to hear & I smiled non-stop for a week. No really, I woke up smiling & my face hurt most of the time. Both of us were super excited to hook up again. We met up one night & did what we used to do best. It was GREAT. Then it hit me, EMOTIONS!! Why? Because I spent the last 8 years thinking about this guy and all the things he made me feel. Years of daydreaming about how perfect we would be for each other if only givin the chance to be together. Really together, not just for the night. I would have felt a little silly if I was the only one saying those things, but he did too, the first week. So the next couple days after hooking up again, he avoided me. No texts, phone calls, emails. Nothing. No response to my initiating a conversation. Which made everything I was feeling even worse. I felt so stupid & rejected. A few days later a message pops up on my phone, "I think you are reading more into this than what is actually there". Hmmm....think think, what to say to sound nonchalant.  After all, if I cant have him,I at least want him to be in my life one way or another. Silly silly woman!! So I explain my crazy feelings were all just a burst of nostalgia. Im over it really I am, so when can we "meet up" again? A few days later we did. Great stuff, once again. Oh man, I think I'm addicted like he's a drug. You know,one of those guys thats everything you want but can never have?? Yep, that's him. Mr Unavailable. I accept the no contact rule immediatly after an encounter. Why? I have no clue! My goodness this man has me feeling bi-polar!! The highs are high, the lows are low. When the next message comes up...buddy do I jump!!  I have never acted like this before. So why start now, and why for him? We had what I assume to be our last encounter 4 nights ago. This morning I sent him a text..Why is there an unspoken no contact rule after we hook up? & he responds by telling me...I'm just going to be honest with you, me & my gf are talking about getting back together. So this me & you thing has to stop. WHOA!! NOW you tell me? I guess the agreement speaks for itself but seriously, knowing someone for that long SHOULD entitle a person to be honest as soon as that kind of idea hits. SO I respond by telling him thanks for the honesty, I will miss our "meetings" * of course the good ole I'm happy for you lie. I'm really not happy for him. I'm really not happy at all. I feel like such a lame. A loser, a weird clingy woman who didn't even have anything real to cling to. So how do you get over a "casual" friend that you werent supposed to feel anything for in the first place?