I love this woman im in a relationship.I could not wait to see her again to tell her.So i emailed her and told her how i felt.How bad did i mess up?

This action is usually viewed by many as an act of desperation and a inferiority complex or lack of self confidence. This will either go bad or worse depending on how the relationship was going and depending on the length of the relationship if this was the appropriate time. But in reality, this isn't something one does for the first time over a phone, email, or text and should be done for the first time in person under the right mood setting so now time will tell all here and if you don't hear back from her, youll know exactly what you did here. Good luck