Thank you for all your responses, she has known for a few months and yes the move would very likely end the relationship with the GF. At this point I feel ending it is what is best for me anyway. I will miss her terribly of course, but I just know it will be devastating for her, she has made me aware of that.
I came close to ending it last night, we had lots of tears shed as we discussed what was wrong and what was right. But then lust took over and we ended up tearing each other clothes off and leaving a trail of them to the bedroom.
This morning we were in limbo again, both heading to work, not saying anything about the situation.