You might up on the biology of panic attacks because you're not going to die, it helps to know that definitively. The anxiety is making your heart race, you're over-breathing 'hyperventilating', you're taking in gulps of oxygen which is converted to carbon dioxide, and you end up with too much carbon dioxide. That's responsible for the feeling that you can't breathe, the spaced out feeling, and also feel pins and needles or tingling in your hands and feet.
Once you realise that however you feel physically - heart racing, breathless etc; however you feel emotionally - scared, panicky, traumatised - your life is not even slightly in danger, indeed in the general scheme of things you're not actually that ill - that's half the battle. Once you fully grasp that the panic loses its hold.
The next thing is to get a CD or book, and learn a coping strategy. They may have like a 5 point plan which you memorise and run every time you get one, and it helps calm you down. It's good to also do breathing exercises to train your breathing, because you can use those when you have an attack.
I can't speak for EMDR because I've never done it, but I was taught breathing exercises and coping strategies that helped me conquer them.
I had tapes I listened to (this was in the days before CDs!) with relaxing music and tapes with a panic attack plan that I used to take everywhere with me.
And for the time being just avoid things that might set you off. For me it was very full tubes, buses and busy London streets - I would feel claustrophobic & overwhelmed and like I couldn't breathe.
I tried diazepam, lorazepam (benzodiazepines), propranolol (beta blocker), Amitriptyline (AD), Prozac, Citalopram and later Sertraline (AD SSRIS) None of them worked.
However, you should do what you feel is right for you, I don't want to put you off drugs because they do work for some people.
Most importantly though do not let a GP prescribe you ADs because they have very little mental health training. You should only accept ADs from a psychiatrist. (I have had this drummed into me by a relation who is a psychiatrist themselves). In your position, I would ask your GP for referral to one assessment by a psychiatrist - I think you need to know if you have PTSD and you can discuss the panic attacks. They will then recommend ADs and/or psychotherapy as well. If you have private health insurance that would massively help. You could go to someone at one of the Priory hospitals (I think you're in London no?) and they're very nice there. They also do daycare classes where you could learn to deal with the panic attacks.
Remember also that you can go to SARC (Sexual Assault Referral Centre) at any point for current or past sexual abuse, and they have excellent counsellors. Potentially you could talk to a psychiatrist there
For me, nothing worked as well as getting to the bottom of the traumas that were causing the attacks, reducing overall anxiety and learning good coping strategies.
Bon courage 