<human>: I want to make this as short as possible:

Met a guy online a month ago and I thought he was the most amazing person that I have ever met. We liked similar things. He was charismatic, fun to be with, and sweet. He was almost like prince charming, but are there such people? What do they hide behind that mask?

After a few weeks...I found out the bad side of him. He lied to me multiple times about not seeing anyone else. I went through the stage of: angry --> disappointment/sad --> mildly angry

I've wrote him a letter saying everything that I wanted to say, and he replied back, but I don't really care to read it because I fear that I might get upset/sad again.
Now everyday when I wake up, I'm haunted by the thought of him. I cannot stop thinking about what happened, what he done and what his purpose was/is. It is so difficult to get him/the event out of my head.

I tell myself: "he's a bad person." "he left me. he didn't care about me at all." "it wouldn't have worked out." "At least I found out now compared to later."
I've even thought about all the bad side of him.

Condense the text into a few key points
<bot>: I thought I met an amazing person, but soon discovered that he lied to me about not seeing anyone else. Now after a couple weeks has passed I'm still haunted by him.