Living with an emotionally immature/stunted man

I live with my parents right now because I left a toxic relationship and have 2 kids. My cousin also lives with my parents. He's 26 and has lived here since he was 17. My mom says he's emotionally stunted from trauma. I think he's just emotional immature. My cousin has had a horrible life from birth until he moved out. He's on SSI because his C-PTSD is so bad he CAN NOT work a job. He's in a conservatorship so my parents are responsible for managing his money. I am not denying that but maybe it's because of how my husband treated me but I have no patience for emotionally immature men. He has no emotional regulation. Anytime anything hard happens or something goes wrong he just has a emotional meltdown. He's crying loudly and it scares my children. Wakes up my 1 year old. He has the emotional regulation of a child and when he's upset he becomes a child so my parents give him childlike coping skills like letting him draw. My 4 year old tried to take his crayons from him and he yelled NO! at her and a grown man yelling at a 4 year old is very scary. He later apologized after he talked about it in therapy but living with him is hard because he does not act his age and I'm just over emotionally immature men. My mom says there's a difference between a man being emotionally immature and emotionally stunted but I don't really care because they all act the same.

Edit: I apologize if I'm coming off as harsh. I just got out of a toxic relationship with children involved and I am not sure how to co exist with my cousin.