hey sorry if this advice is crap, i never had any eating disorders, but i think that if these friends are close to you, then you should tell them about your eating disorder. with my group of close friends, if one of them was suffering from a disorder, and he told us, then i would do all that i could possibly do to help him through it, and im sure that all my other friends in our group would do the same.
think about how great it would be if you got on this holiday, and you tell your friends about it, i for one, would think that it would bring you closer as a group of friends. and during this holidays, after they all know, you could as friends work out a plan to help you get through not only the holiday, but also the rest of your battle with this disorder.
but i think if you get your friends involved, you will overcome this probably alot quicker than you would yourself. ask yourself this, what have you got to lose?
but, that aside, if you would like to keep it to yourself, maybe always have a bottle of water next to you. the more water you drink the moreit will fill you up, sure you go to the toilet alot more haha, but it could keep you occupied.
buona fortuna!
ps. and dont forget that there are always plenty of poeple on this forum that can offer you some amazing advice, so never forget if you have problems ask us!