I'm not 100% sure I believe her story - breaking up because you might not be there in 8 months' time sounds crazy - very inflexible, to say the least. It may be she's still not quite sure of her own sexuality, met a guy and surprised to find she fancies him or something like that...
Anyway, as for you, there's not much anyone can do when they're dumped. Don't feel you have to be good friends if you don't feel like it, though. You might well be better off keeping as far out of her way as possible until your own feelings have cooled a bit. Sorry you're caught up in a storm like this - it's nothing to do with being gay, I don't think, the same thing happens to straights