Hey MisfitMel!
You're in India! If you're around Delhi or Chennai, I have a cousin & a friend.. both girls... there who have both dealt with depression and can be just friends/company in a new country (if it is so)
About the boyfriend... just give him some time to think things through. A lot of people don't understand it and ask why we can't just "think happy thoughts" or "focus on the good things". Your boyfriend may or may not be so, but giving him some resources about depression might help him. Beyond Blue is a pretty good website, I've found.
The abruptness might just be due to the suddenness of all this information about something he doesn't know too much about. Hearing that you have had suicidal thoughts before, when a he simply cannot see it in the wonderful person he is with now, may have shocked and worried him. He'll be wondering what else he doesn't know about you, and if he's with a whole different person.
Give him some time to figure things through. Try not to email him constantly and ask what he's thinking because guys tend to like space. It's really hard, I know... but just try :D
I can't believe I'm dishing out advice like this! But hey, I've been through this exact phase :)
If he's worth it, he'll stick by you and try to find out more... and support you even if he doesn't understand. You aren't that person anymore, but it is a part of your past and he'll be able to accept that with some thinking.
Take care! Enjoy the mad, mad country that India is!
Oh, and PM me if you want to chit-chat privately.