Yeah i agree with both previous posts, you need to open up about this problem with someone who can understand you and that knows how to help you i.e a counselor.
Your boyfriend seems a good person and seems like he loves you allot, i think you should try and trust him more. Trust is a difficult thing to give, but once you give it away you will feel much better and secure.
Think it this way, if he loves you he will not betray your trust ever, if he is destined to betray you, he will do so no matter what you try to do to stop him doing so, so i suggest you choose to trust him since he always gave you respect, and he will appreciate this act from you and im sure your relationship will become much stronger.

Goodluck dear.