Vain, one thing you need to remember is not to be too hard on yourself!! I think you're having these anxiety attacks because you see her, think "I'm over her", then realize you're not over her and get really angry at yourself for being weak or something like that. That was the hardest thing for me getting over this guy recently - I would think I was doing really well and suddenly I'd have this terrible day and think I'd taken 10 steps backwards. Having a bad day or a missing-her episode is ok, and it doesn't mean you're not making progress!
Also, this might seem kind of dumb, but I found it really helpful to sort of psychologically shift my reaction when I accidentally thought about him. So - when she suddenly pops into your mind, don't freak out or get angry at yourself, don't get frustrated. Just gently put those memories back in that chamber of your mind reserved for her, and gently lock it back up. Eventually you'll be able to think about her again without hurting and missing her, and then you can let those memories go. But right now you miss her and you don't want to give up your good times together - don't think that you have to completely forget her. At least not yet.
