Get ready for the long haul. If your boyfriend has been cheated on before, he will assume you are doing the same to him. He just might drag all of his past relationships into your relationship. The best thing to do is get together with him and talk about all of his fears and your fears as well, get it all out in the open. Then decide what to do about each thing you discussed. If he doesn't want to discuss anything with you, then you aren't going to have a healthy relationship.
If you've been talking to other guys on the internet, then you need to let him know that it was only friendship and nothing more. Remember that relationship problems can stem from poor communication, so try to be as open as possible. This will help you and him equally.
He is going to think that you're cheating on him when you're not. You need to talk to him about it he is way to protective over you. He needs to trust you. Without trust a relationship can't last