I told my boyfriend about 2 guys that asked me out which I said NO to, 3 weeks after it happened. We were also broken up that day if it matters. I was scared to tell him because he gets so mad and one of the guys is kinda like a friend to both of us, we play sports with him but we don't hang out. I didn't want him or me to get into a big fight especially at the social club we belong to. Anyway does this make me a bad person or something because now my boyfriend wants to break up!

I don't think that your a bad person at all hun. If it was a girlfriend you had told you wouldn't be questioning it.
I don't understand why you told him weeks later though. did it come into convo? Your b/f needs to see that other guys will and find you attractive just like he does and boys will be boys and go for the kill. If your b/f was secure within himself he wouldn't be angry at all maybe a little jealous but that can be cute. You shouldn't feel scared to tell your boyfriend anything. and if that is how you feel then that is the real problem in my eyes.
waiting weeks to tell him would have only made him take it harder. I mean the 1st question I assume that he may have asked was why didn't you tell me before? .......... Then the argument starts.
If I were you I would feel flattered that the guys asked me out but at the same time I wouldn't rub it in my b/f face. If you were going to tell him you should have done when it happened not 3 weeks later. He probably thinks that you were trying to make him angry.
Let him cool down and explain that the guys asking you out was flattering thats all, then maybe he will see that he can also do the same. GOOD LUCK

I wouldn't say you are wrong...but most men don't want to hear that you have been asked out. You might like the jealousy it causes and it shows you that he does care, but guys feel threatened and it can effect his trust. Men on the other hand love to brag about girls checking them out or hitting on them, and that should be fine. If the shoe were on the other foot he might laugh it off if it upset you. Men usually have double standards on other men/women. You cannot look at or flirt with anyone because YOU might do something, but HE can. I would keep things like that to yourself. I don't feel it is lying. If you took another guy up on it....that's another story. If you are afraid he will find out through the grape vine, I would address it at that point. Say something like "I didn't tell you because it was comical to me that another guy would think I would go out with him when I have you!!!"