Just looking for a little comforting advice...?

You should tell him, I understand your fear of the past repeating itself but there's a really good chance it wont, Secrets no matter what they are, are never a good thing. Plus being pregnant is a wonderful thing yes..but it also has moments that aren't so beautiful, with all the emotional changes and bodily changes you experience, you'll need his support. Especially during the first few months. Enter into this with confidence and fearlessness...don't worry about the what if's that will drive you crazy try and focus on the hear and now and right now your pregnant with a precious baby! Enjoy it! and like you said God forbid you have to go through the same heartbreak again, but if you did you shouldn't have to do it alone. Best of luck to you...I hope with all my heart that everything works out for you.