Would it be wrong if I keep comparing him to my ex?
Why can't you stop comparing him to your ex?
Yes, I can't stop thinking about how great my ex was and how I wish I could have him back and we never broke up.
It is good to move on in your life. The breakup happened for a reason so you should move forward and live your life.
You don't understand what I'm going through.
It sounds like you're the one holding yourself back, you will never find happiness if you keep thinking about your ex. Focus more on this new guy instead.