OK...aside from the fact that Bill Clinton isn't running for President and has nothing to do with this...
Donald Dump knows DAMN WELL that he, of all people, cannot comment on Bill Clinton's prior infidelity as he sets himself up to be opened to questioning of to the two wives he already cheated on (assuming Millania hasn't been cheated on already, of course.). And Hillary can easily invoke "I made a vow at my wedding to stay with him for better or worse. Did you stick to your vows?"