I am sorry for your situation, this sounds terribly scary. You first need to accept the facts: 1.) You did cheat on him; 2.) You can't blame alcohol for your decisions that you made while drunk, even drunk, they were your choices. Cheating doesn't "just happen;" 3.) You need to talk to your boyfriend.

I don't mean to sound harsh, I have been in your shoes. I cheated on my son's dad as a way to seek revenge after he cheated on me- although after it happened (and the alcohol faded), I felt horrible. My solution was to not tell him, and in the end he found out (they always do. S*** hit the fan. It was a nightmare. I found out I was pregnant a few weeks after.

It wasn't until the paternity test came back that he started on the path toward forgiveness, and in the end, it was a large part of why we could never work. Not so much the act of cheating, but the act of concealing it. My first suggestion is to get a pregnancy test. You HAVE TO KNOW if you're pregnant ASAP. I can't stress that enough.

Secondly, you need to tell your boyfriend what happened. Be prepared for a knee jerk reaction, chances are the aftermath will hurt. It is only through being honest that you're able to start forgiving yourself. Your mistake does not need to define you, however. Good people do bad things. Let him know it was a lapse in judgement and be accountable.

If there is a deep love between the two of you, he may learn to forgive you in time. You cannot make him do so, however. Be patient, gentle, and no matter what mean things he says (as I'm sure that'll be part of the knee jerk reaction), remember that you are still a good person, you just did a bad thing. I wish you luck and truly hope this works out. You have a hard road ahead, but you can get through this.