It's ok to be angry. It really is. You have every right to be angry. I think that while forgiveness is a good thing, and is a healthy thing to do when one is ready for it, there is also a time and a place for anger. I am glad you are expressing your anger here. It definately was NOT ok for your mum and step-dad to do the things they did to you. And even if you do get past the anger to forgiveness one day, that still does not mean that you think it was ok for them to do those things, cuz nothing will ever make it ok for them to have done those things.
I hope that you can get to a place in your recovery where you don't feel so dirty all the time...cuz you are NOT dirty. It is very common for survivors to feel dirty, though, and many of them do scrub like you described. The other things you described are common as well...the nightmares, wetting the bed, throwing up, fear of going out. Are you in therapy right now, Jamie-lee? If not, ask your mom to help you find a good therapist, because these are all things you can work on so that you can be more of what you would consider to be a "normal kid". You deserve to have that opportunity, Jamie-lee. Please know that I'm here if you want/need to talk.