If you listed hours in the future on your application, you might want to contact the schools and say that you've had to step away from your volunteer work at XYZ Hospital and will not be completing the N hours that you had noted on you application. That's all.
I don't know that this is "bad terms" You didn't commit a felony or even break a hospital rule. If anything, you feel disrespected because you have been asked to enforce a rule only to have the hospital fail to back you up and even to change their policy, on the fly, in certain circumstances, making you out to be the unreasonable and rude person who enforced the written rule when the unwritten rule is that the rules don't apply to everyone. You were pissed and I would be to. Don't worry about it. The hospital will not black ball you and the adcoms will not find out.