It may be a quote that belongs to another person, but I only know it as said by my stepfather - and I'll share it with you: No one can make you feel badly without your permission.
You are giving this girl free rent in your head. Mean what you say and say what you mean. When she offered not to go, you told her you wanted her to go and have fun. Then you immediately felt rejected by the response. One of the hardest things we have to do sober is to stop lying. You set yourself up for heart ache. You knew she'd go if given permission, perhaps even if not. Ask yourself why you set yourself up for this. You already know who she is, so you don't have to question her motives. You should be examining what you say, why you said it, and the result you achieved. One of the questions we answer when doing personal inventories is " How did I attempt to manipulate the situation?". In this case, you seem to want to sabotage your own self, and then to wallow in the drama and misery this brings.
Even when sober, us alcoholics can create lots of drama! I can't tell you what to do next. I can't tell you not to obsess over her, as you will do what you will do. I can say, if you're going to AA, go with sincerity and intensity. If you can be relieved of your need to drink, don't you think you can ask to be relived of the madness that is this relationship?
You need some peace. I hope you find a measure of it