My 6 & 8 yr old stepdaugnters are being physically abused my their moms husband.?

My step daughters live w their mom and her husband. They admitted to me they love being w me because they dont have to go to bed with their head hurting. I asked them "what do u mean"? They explaned to me when they get in trouble thier moms husband grabs them by the neck, slams them against the wAll (around 5 ft fm the ground) and drags them down to the ground still by the neck. I asked them what their mom does and they told me she just says "stop, okay thats enough" speaking to her husband. He hits them all the time and the kids even said their moms husband crys to the kids and asks for forgiveness. Sound like hes abusive. I am going to call cps but they live in another state. They are visiting for summer, its my husbands kids and neither parent nas custody. Pls help!!!