well at least he had the decency to TELL you. and if they just met two weeks ago, it may have taken some time for him to decide whether THAT path was worth pursuing. i wouldn't call it cheating unless you two had some pact to be exclusive.
these things happen, and what we thought we had sometimes just isn't. you yourself said you had doubts due to the age difference, and were resistant at first. so the good news is your inner warning bells are still ringing and thankfully it didn't take 6 YEARS for more to be revealed.
so now, you get up, get something to eat, take a shower. you have a new job starting soon AND six weeks of YOU time ahead of you. i'd KILL for that much time off!!! now is the time to explore YOUR new world, get to know your environs, find the best coffee stand, thai food joint, yoga studio, whatever. get out of the "city" and find some nature. do silly touristy stuff. life isn't over, its just beginning!