First I think you need to keep telling yourself that your boyfriend loves you for your and only you. And that the reason he chose you was because you mean alot to him and that you're very special to him. Try reminding yourself daily and think more positive thoughts to boost yourself everyday.Okay, once that's done. When you feel yourself getting the feeling of being jealous, take deep breaths in and out. Try calming your senses when you feel jealous, it might turn out its fine.
Being calm keeps you from doing silly things that jealousy might provoke you to do. Sit out and think it through. Is there really a problem?, does your boyfriend seem to be letting of the wrong impression?. Once you have thought it through and you still think it might be a potential "threat" or you just can't deal with it. Try gently reminding them that he is your boyfriend or walk out for a breather.I think the key to jealousy is trust, try and remind yourself of it too. Maybe even try talking it out with your boyfriend, you can solve it together.