I agree with what the other posters have said. You are responsible for your own happiness, not anyone else's. If he has trust issues, abandonment issues, whatever... those are HIS issues! He needs to work through them. He is manipulating you. I'm sorry to be so blunt but he is.

This is not healthy for either of you and both of you need help. Yes, you read that right, BOTH of you need help. Him, to deal with his problems. And you, to deal with the emotional fallout of having someone you love manipulate you like this. You have a past. Guess what, so does he. He's not a perfect angel that never made a mistake. The healthy reaction for him would have been to either talk and work through it, or to break up.

Another thing to think about, how are you so sure that he wouldn't have reacted the same way if you had told him straight away? The thing is, he is not stable right now. I really hope that he gets the help he needs and that you can talk to a therapist as well. Your mental health is just as important as his.