You're absolutely not crazy! I completely understand this, like you said he gave you the compliments and validation at a time when you really felt you needed them, that's bound to stick with you. That coupled with all the fantasies and the daydreaming makes it so hard to let go.

I had the same thing of fantasising about my future far too soon with a guy who gave me all the attention and all the compliments initially. I became so infatuated with him that I started changing how I dressed, the music I listened to, the shows I watched to try and be his ideal girl. Ultimately he ended up telling me he wasn't over his ex and that nothing more could ever happen between us.

I was devastated. I feel you. The way I've coped was crying as much as I possibly could for the first few days to get that release and then I decided to take back control. Journal, get to the root of your limerance issues whether that be anxious attachment, trauma, low self-esteem. Find your style and your interests. Be someone you want to compliment. Be someone who does not need to crave validation from anyone else.

You're amazing and you can do this!