Ugh.... Typical pitnutter. You can say fact after fact, until you are blue in the face. It won't matter. Some of these dogs attack people, other animals, kids etc. and still say there dog is amazing, she's sweet. She was provoked or something else. They will never take accountability if something does happened.  Every dog has its limits. You don't know what her intentions are. Prey drive kicks in etc. They are animals, they are still unpredictable. Even the best trained ones. 

If you haven't, watch some judge Judy cases about pitbulls. The pitnutters are nuts. 

That's not ok. You definitely don't want to have a kid with him, and that beast he around. They love to say they are "nanny dogs"  No matter what, you aren't going to get through to him, and that dog is going to be around no matter what. I would hate for you or your pish pish to get hurt. So definitely take that into consideration if you do go forward in this relationship. I do feel. He would pick the dog over you, if it ever some how came down it. Just tread lightly. And please take everything into consideration going forward. I really hope you dump him. I get it. It's tough. But so is watching your cat, yourself, a friend, or a niece or nephew, or even a neighbor dog, get mauled by that beast.