... . I can't help to think that it is disrespectful of our 4 1/2 year relationship to rebound that quickly. Even if it was tough, we had a wonderful love story that felt so unique.
Disrespect is typical, don't beat yourself up over it. it's part of the condition and accepting that will help you get over this quicker. I would also suggest that while your wonderful love story felt unique it was more than likely fake on his part.
Don't worry about the replacement... . she will be here soon enough. Go out and make a new life for yourself. You can have the happy life that he cant so what are you waiting for?