Pregnant by a married man...who apparently is abusive?

There's a 23 yr old girl who was having an affair with a married man who is 40. They broke up because she started to fall in love with him and he didn't want to get emotional. The next week she found out she's pregnant. She knew he had a temper but apparently he beat his 6 yr old son untill he had a bruise or 2. And now he's admitted he one time threw his newborn (now 2) on a pile of blankets out of frustration. And just this week his 6 yr old wouldn't listen and kept misbehaving so he grabbed him and got in his face then threw him to the ground and 'pushed him around with his foot' ....those are the 2 kids he has with his wife...now there's the 23 yr old who has fallen for him and is knocked up..she wants her baby to know her daddy but what should she do? He's never been violent or angry in front of her and he's never even raised his voice at her