I'm not sure if this is the right place to post this but I'm having a bit of a problem. So my fiancé as two kids a four year old girl and a two year old boy. We usually get them three days a week and the days are all in a row. So on the second day his son had a huge gash in his forehead. When my fiancé asked his mother about it she got all defensive and said why do you care? We asked his daughter when they got home and she said mommy wasn't watching him and he fell down the stairs going into the basement which is about 20 steps I think. (Going off of what he says.) Now we both noticed that when his son would speak he would stutter servely he couldn't get one word out properly. He wasn't doing that the day  before so in less then 24hrs he developed a stutter. Is that even possible? He wasn't always the best talker he can't really speak in full sentences but he never had a stutter. I told him to confront her about it but he tells me she'll never admit that he fell down the stairs and try to blame us for his stutter saying something like "oh he wasn't doing that when he was with me." He also said he wouldn't call CPS on her because he did that once before because his daughter had bruises on her back and butt and said her mom beat her when the social worker  interviewed his daughter  they did it with her mother sitting next to her and  of course she didn't want to say anything. The social worker told him that she can spank her children if she wants to. He has no faith in CPS. I just don't know what to do his ex lies about everything I feel like if I call CPS myself I don't have any evidence of what actually happened to him. The only thing I'm going off of is what his daughter said plus I don't know if hitting your head hard enough can cause you to develop a stutter. I took pictures of the gash but I just don't know the next step I should take im so worried for my fiancé son.