Sorry to hear that Chayse...it's never any fun to go through a break up, regardless of which side you are on.
I have to say though, (Based solely on what you've written here...) that if this was enough for her to want to break up, then maybe it's for the best? There are a lot more serious things to disagree on in a relationship than cigars after all...
Definitely wasn't good that you hid it from her though, it's been my experience that when I've hidden things in a relationship, it's never (evereverever) ended well.
If I could offer any advice, it would be to try to find a girl that you can be as honest and open with about cigars, etc as possible. Besides, there are plenty of women out there that are okay with cigars as well as some who are enthusiasts themselves!!
But yeah man keep your head up, as I recall, you are still a young dude so you have plenty of time to look for a more cigar tolerant relationship!