It seems odd…but you use a light board and/or a pulsing tone which goes back and forth between ears/eyes/hands (a pulsing vibration)…it’s hard to explain. But it focuses and relaxes you sort of inducing a dream-like mind state (a bit like hypnosis, but you are fully conscious). You’ve probably noticed that PTSD causes lots of dreams/nightmares? Well, EMDR helps you process memories in a similar state of mind.

Anyway, a therapist can explain it better… but it is very effective for your type of past. It is also often beneficial to take some sort of medication for at least a short time because EMDR means facing your past which generally is upsetting at first.

If you want more information check out
http://www.emdr.com/

But as someone who has gone through it, I can say that it is difficult but effective
References :
http://www.emdr.com/
personal experience