You've made a good first step- telling us about this.
First of all have a number of articles here at Scarleteen that you can read. This is a pro-choice site, and be sure we will support your decision.
Dealing With Rape gives advice on steps to take after the incident and the healing process.
Abortion: A Woman's Story
Granny Panties- A user's story about her abortion.
Alongside these two articles you will also find resources- phone numbers and websites, that will provide further information on obtaining an abortion.
Another thing you're going to need to do is arrange to be tested for STDs and STIs- the sooner the better, and then again in six months, in case something didn't show up in the first screening. I know its scary, but if you have something and it goes untreated, the outcome could be much worse.
You can also head to our Support Groups forum, where you will find volunteers and peers who may have experienced similar things, and are ready with open ears and virtual hugs.
The best of luck to you in this difficult time.