Most Helpful Girl
... And it's not really getting any better...
With this being said and you know the truth in your own head, you are Now being this Honest John in Openly admitting that you are Smitten... In love with another girl.
Before jumping back into the saddle, it is best to tell your current cutie that may not be such a honey right now, that you don't want to be hooked a the hip with her anymore, that you want to be free and give yourselves a chance to grow elsewhere.
Start out slow with your flow with this newbie, feel her out. Nurse and nurture a nice friendship, which apparently you have already started, and perhaps you will both find that you will one day be riding off into the sunset.. happily ever after.
Good luck. xx
Most Helpful Guy
There is nothing wrong with you for losing the feelings for your current girlfriend. That happens sometimes. However, you put yourself in a position where you were tempted by someone else and that is unfair to your current girlfriend. You haven't given her your undivided attention. Learn from all of your mistakes!
What's done is done and it can't be undone, so you need to break up with your current girlfriend. I wrote a myTake on how to break up:
Break up with your current girlfriend before you proceed any further with the new interest. You don't need to tell her that there is someone else but she will probably realize what has happened. However, if the topic comes up, don't lie to her; she has devoted a year of her life to you and she deserves honesty.
After you break up, expect to feel some remorse about your decision, even though you have someone else waiting for you. Also, once you start getting into the relationship with the new interest, expect some of the magic tot be gone, because it will no longer have the taboo/forbidden aura.