Yeah, I believe it's very important to be on your own for a while. We all try to fill that void too quickly but if you are with your new girlfriend thinking about your ex all the time it's definitely not a good sign and not fair to your current girlfriend. And if you thought that you would one day want to reconcile with said ex girlfriend, pursuing her while she is dating and you are dating is not helping you. You might need to remove her phone number from your cell phone or if you are sick like me and memorize numbers, turn your phone off when you go out. Or don't bring it at all. Just for right now, while it's still raw and still tough.
Remember that she is always going to have a little piece of you for the mark and impact she has had on your life. It is possible to love her and not be with her and I think you know that even if you were together today, it probably wouldn't work out because of how hurt you are and how she doesn't want anything to do with you. If you have a fantastic girl in front of you and she makes you happy, you should concentrate on that and treat her the way you should have treated your ex (assuming you were the **** up, most guys are). I mean you can't help how you feel and if this new girl isn't doing it for you, you have to let her go not only for her benefit but for yours too.
Waking up next to a beautiful girl,
Step outside and say hello to my beautiful world.