Why does it sometimes happen this way?

It seems to me that sometimes no matter how nice you are to someone... They are always cruel or mean in return. I have personally spent years being courteous to my ex-husband but to no avail...
What gives? Will he always be needlessly cruel and hurtful? Unfortunately it has now been 4 years since our divorce and it seems worse than ever... I will have to leave it to karma to resolve this for us. He is so strongly opinionated I think counseling, therapy and the like would not make any difference. His superiority complex would remain intact! I shall prevail and weather the storm! Only 10 more years to go!