How do you?

I went to see an old friend tonight. She wasn't home, so I sat around with her sister and waited for her to get back (she never did.) Their mother's boyfriend was home and as soon as the sister walks into the house he starts smarting off to her and calling her a stupid bitch (she's thirteen). So, he walks up to me, pats me on the shoulder and says "Sorry about that," and walks upstairs. I don't see him again. This is not the first asshole this woman has dated. This woman has children to think about but she is drawn to this hurtful, abusive type. I don't even want to know how this guy treats them when they are alone. It made my heart heavy and my head hurt. And it's in situations like this where I pray and ask God all the questions. Questions to which I don't receive answers quickly.