Wow I am sorry. But you did what you could. People are just morons, they think they are cool because they drive drunk all the way home and are just fine. But then something like this happens. It is a wake up call for everyone.
I am sorry you could not get there in time. I could not see the accident for myself but sometimes there is nothing you can do. I know that if you are an EMT the first thing they tell you is 'You are not here to save peoples lives you only extend them'.
I do not know what consolation this is to you really I do not. I myself have never been at a fatal accident. And I know that it does not help to hear "You win some you lose some". So spread the message, that drinking and driving is bad. Become a designated driver or start a program. My town where I go to college has a free taxi service. They call it safe ride, basically it is a service to discourage people from diving drunk.
I do not know what else to say really. I want to be of some help. I guess the only thing you can put your heart at ease with is the fact that the boyfriend will go to jail for what he did. Though it is incredibly unfair, he gets 3 years max I think.
I will leave you with this. If you only dwell on "What Ifs" you will destory yourself. It is ok to feel greif but try and move on, maybe next time you will save someone. Maybe next time it will be worse. All you can do is strengthen you heart. I wish I could be there to physically listen to you and give you comfort but I cannot. Feel free to PM me whenever you like I will always listen.