Its better to have a lousy father then not have one at all. Even if you have a lousy father you can still learn from him. You can tell yourself, "I'm not going to be like him, I'm going to be better". Even if you have a lousy father his going to love you no matter what.
Yes, i would turn them in to the cops, because i wouldn't want my kids looking up to a murderer. The kid's are going to believe that its okay to murder another human just for the fact that they're mom has done it, and no one wants they're kids running around with that kind of mentality. Its not right for someone to be free after they committed a crime that big.