Rampage!

I'm 8 months pregnant and all together me and my husband have 4 children and the one in the way. Well 2 of his children aren't mine which are 4(boy) and 6(girl). Their mother is in good health and works but doesn't have her own children. I have all 4 all the time because they all live with us. Now the 4 yr old boy is very disrespectful and he fights my 1 yr old daughter and always tries to hurt her because he does have a few anger problems. So today he made my 1 year old fall head first onto the floor I disciplined him because when asked he said I tried to hurt her because i was mad. So his mother called out the blue and talked to his sister and she told her he was in trouble now the mother called my husband and talked alot of noise about what she was going to do to me and etc. Now my husband called to check me about disciplining him because she called him. Am I wrong for getting offended and going off on the both of them because neither one keeps the children but wants to call and check me about the children?