I am not a teenager anymore, but I can understand the feeling of jealousy, I am sorry your feeling so hurt by it. It's teenage hurt, one of the first ways you learn about pain in male/female relationships as you grow older and learn.
I am not sure how to tell you how to react, seems like you've acted appropiately so far to the particular situation.
Marj , may have possibly had a point, you may get advice appropiate to your age level on the teen board.
But your feelings are definetely very mature and felt by people of all ages, I am sure...I am 24 myself and still deal with these feelings....Maybe jealousy stops at 40?
Usually in your type of situation, you may be feeling a little worried that your boyfriend might like someone else better. You are both very young, in my experience, young boys, especially teenage boys are a little bit emotionally immature, and also from my experience, it get's even worse when there in their early 20's!
I remember when I was in my teens, many students in highschool were experimenting having their first romantic-type relationships. Usually (from my experience) the boys find it just as interesting to try out dating as much as the girls do, but I think girls tend to
have different ideas of what they want...something that holds true....long well after highschool.
I think many times boys (and girls too) get excited by all the attention they are getting , especially in a school situation, but I think girls are ok with having 1 boyfriend, whereas for boys, it seems, the more the merrier--sorry for how that sounds, but I really think it's human nature, being expressed. I think telling your bf how you this made you feel was a good thing as he will understand how his actions affected you.
So this boy is probally just enjoying the attention a little bit.
As for how you feel, like I said before seems like you've handled the situation very well by talking to him. This is great 'practice' for you and all your future relations.
You'll learn by experience, this is real life practice your getting which will help you for when you get older.
I hoped that helped at least a little but. Remember to not put all your apples into one basket , keep yourself interested in other things as well! And best of luck to you !!