Does the Property Settlement Agreement stop when Alimony is terminated?

My husband's ex-wife remarried. She tried to continue to collect alimony, even though she was being supported by her current husband. To our surprise, NJ courts actually did their own 'investigating' proved she was in fact remarried & awarded my husband 20 weeks of alimony overpayment. Kudos to the courts for 'busting' her. Shame she wasn't held in "contempt of court" for collecting something she wasn't rightfully entitled to. My question is, now that she's remarried & alimony has been terminated,does the property settlement agreement terminate as well?In the divorce,it stated I was to pay for portion of our son's college expenses. Our son was emancipated over 4 years ago. He works 2 full time jobs. He pays over $450/month for a new truck & lives out of state in an apartment he pays for himself. If he is able to financially support himself & afford luxuries,why should I pay for something he's more than able to do on his own? Any insight would be greatly appreciated! Thanks for reading.