I don't think your boyfriend is being honest. Two years is a long time to "use" someone and personally, I think he's playing you both. Are you sure she's pregnant? If so the question you need to ask yourself is how are you going to deal with her because she will be a problem and unfortunately, if she is pregnant he has to deal with her for at least eighteen years. If I were in your shoes and found out my boyfriend had a side chick and she was pregnant, I would cut my losses and move on. You deserve better than to be with someone who will cheat on you and risk your relationship by not practicing safe sex. Let her have him.