You have to build trust in your boyfriend & gain some confidence girl.! Think of it this way, he wouldn't have picked you, over probably every girl he talks to/knows if he wasn't cookoo bananas about you.! Just act cool, and think of it was 'they are having a conversation, like me and a guy friend of mine, would too!" and simply relax. I had this problem before, but sometimes it's better to position yourself in his/other people shoes, before you jump to conclusions. I know it might be hard for you, since you have been cheated on, but know that surprisingly, not all guys are the same, and you have to take risks in relationships, not always hide in a shadow, because you're afraid of being hurt.
If he's getting/is already mad at you, just show him you can trust in him, and gain confidence in yourself, guys think that's sexy/nice, and who knows? He might even like you more. ;)