I think the first thing you might want to ask yourself is--are you very serious about your boyfriend? How did you leave things with him when he moved away? How does your relationship work? Do you have a mutually exclusive agreement or something like that?

You say you want to go out with your friend. If so, maybe you should speak with your boyfriend about this. You may even find that it is time to end the relationship. Then again, it may be that you both decide to leave things open--you are free to date others, even though you still might want to maintain a relationship with your boyfriend and see him if he comes to visit. A long-distance relationship is possible if both sides are committed to it, but it sounds like you might want to explore other options with your friend.

Sometimes it can be hard to make decisions on these issues, so you really need to listen to what you want and not what other people want. Even though you say that your boyfriend is both serious about you and a big guy, you should do what is best for you. It wouldn't make sense to stay with him because you are afraid of what he might do. If you think he may become violent or otherwise scary (harassing, etc.), check out the DEAL WITH IT! relationship resources. His size or position on a sports team shouldn't be an issue at all.