Step Mama's Issues

My husband and I are in a long distance relationship. I live close by his son so I take him to spend time with daddy when I go....Sometimes the son doesn't listen and I have to be firm with him. When I do his tells his mom and she gets rude....She hates me and never tried to have a mature relationship with me and causes so much drama or keep the child away.....So now the child told his dad his mom is the reason he is mean to me.....Anyways the child now wants me to take him to see his dad but I'm tired of the drama it causes. Is it fair to make my husband talk to the babymama about causing drama and if she continues I will not be involved anymore???? I would like for her to approach me in a respectful way about anything regarding her child because he does lie sometimes since he knows she hates me...Would you still take the child????