Not giving any legal, medical, or moral advice. Just stating the facts:
Anyone knows that when you mix alcohol, medications, or any other Drug, your normal judgment (including the ability to make key critical decisions such as consent to sex with someone) is drastically impaired. Based on your situation you presented, mixing drugs or medication and alcohol is a really bad idea anyway. You already rendered yourself vulnerable by the taking in of these things because these things impaired your judgment (and more than likely you knew this because these things are taught in school) and this most likely led to the things that occurred because of how others reacted to you (particularly the males) in seeing the state you were in. I will say that young men taking the high road would have left you alone. However, some man apparently saw an opportunity presented itself to get to you and you did not have the judgment to stop it (due to being under the influence or intoxicated which subdued your own inhibitions and I am NOT saying that it is okay at all to take advantage of someone under the influence either).
This sounds like based on what you said and how you described the situation, the actual events that had occurred could have gone either way. The thing to know is you didn't have the proper judgment at the time to emphatically stop this from happening. This means you need to stay away from alcohol and only used medication that is prescribed as directed. It sounds like you put yourself in a situation where you were already by yourself (around other people that could do this to you), so you left yourself vulnerable. Some guy apparently saw "an easy target" and preyed upon that (as it can be perceived). These kinds of things happen even around people you are acquainted with and think you know. You are probably feeling guilty about it and that is why it bothers you so much.
You could look at this one of two ways, you were under the influence and had impaired judgment so you really did not know whether or not you were saying yes or no if it even happened (and we do not know that it really did).
On the other hand, there are "date rape" drugs out there. In these cases, according to what I have heard, the man knocks the woman out completely by slipping some drug into her drink. She is unconscious and can't do anything. The man in these cases has his way with her. She usually wakes up naked or something else. I do not think this happened to you based on what you described.
Your attempt to prove rape could be very difficult. As other posters stated there are a number of different plausible explanations that can account for the morning after.
I would further advise you to stay away from alcohol or drugs (never combine them together) and stay away from parties if you do and be around trusted people you know. Doing anything else or putting yourself in another situation where this could happen makes you really vulnerable and puts you at great risk.
Not to scare you... these are the facts. There are weird predators out there (some of these people are really depraved), there are a number of STD's, and there is the knowledge that you need to have the proper judgment to know when you are giving or not giving consent.
The law broadly and generally defines rape as the forceful sexual advances of one person onto another without the mutual consent of another person (with certain exceptions like the age exception, I.e. you need to be of adult age and so does the other person, etc...). based on what you said, rape would be difficult to prove here under the broad scope of the law. If you disagree, you can speak with local law enforcement officials within a reasonable time period, but you are also subject to scrutiny of law enforcement if you do because of the drugs, alcohol, and other things, depending on what you say to them. There's another catch-22 and it could work in a negative way against you.
What I would say, not that you know all of the outside facts (and from a person not knowing the actual specifics about the situation you described) is: If I had the choice, I would do what I felt was right to make me be okay with it and above all- learn from the experience and be glad you're still alive and survived through it. If I were there, I would have been a total gentleman and saw to your safety.
Sincerely,
The snowyowl
