First, you need to charge the man with rape and have him arrested.
Second, you need to get other friends - Obviously this friend is not a true friend if she let this happen to you. You were taken advantage of, and friends do not take advantage of one another. All the best to you!
Addition: If "Friend" was present, she should be arrested also. Unless of course you discussed getting involved with them in this manner prior. If any of you ever hinted on it or talked about it or considered it and you said anything outside of a firm "No!", you have no reason or grounds to be upset with anyone.