I think you may be lucky the relationship was only a year long. Even tho you can gather a lot of memories in that time, if it had been say - 10 years long - it would have been much worse!!
It sounds like you made the right decision since the distance was against you as well as other issues. You shouldn't have to suffer from guilt as well as other emotions while trying to keep the relationship going.
So just figure you made the right decision and try not to analyze things. Move forward with a clean conscience, and you'll be fine.

I wish you the very best, and please take good care of yourself. God bless! Hugs, Lee