You're a very nice girl because you consider other people's feelings first before your own. How much do you like your crush? Try to really determine what you want and who you want. You want to be with your crush because you're developing feelings for him and you want to stay with your boyfriend so that he won't get hurt and you want the feeling of being loved. You both want them but try harder on deciding who to pick.
When you're absolutely sure, then think of ways to tell your current boyfriend how much you appreciate him and how much you care for him to give him the truth that he deserves. Just because you'll tell the truth, it doesn't mean you'll hurt the person. There are other people who are more grateful for the truth and do not feel hurt. You will never know so don't assume. Focus on yourself. Please yourself first before pleasing others.