I too counsel you to be careful. The man is extremely narcissistic, he will NOT respond to you divorcing him like a normal decent person would. We all tend to think people are like us. But this man is NOT like you, he is another beast entirely.
He will likely switch between three channels: Self-pity, Charm, and Rage. He'll start first with Self-pity - you saw that this morning and last night. When he realises you're done with the relationship, he'll switch to the Charm channel. He's used to these approaches working on you. When he starts to fathom that you're serious, the Rage channel will come into play, and he will start flicking between the three channels with increasing rapidity because he'll be trying to see which best hits your buttons. Recognise those buttons in you, because they are the buttons that got you into this situation in the first place. IE compassion, sense of responsibility, kindness, attraction to his good looks, attraction to his sexual interest in you, attraction to his charming persona*, worry for DSD, sense of decency, care for others.
His flicking through the rage, self-pity, and charm channels will be very confusing to you. This is also part of the narcissist's strategy: to confuse their target into staying still so they can work on them more, make them doubt themselves, wear them down. Be prepared for all of this. Also, be prepared for the hurtful Rage channel to shift into violence or threatened violence, including - possibly - against himself: he'll see if he can intimidate you like that as well.
*That charm is merely a pretty mask. It doesn't reflect the real (exploitative, scary, and creepy) him.
Another point I would like to make is with regard to DSD. You're going to have to steel yourself to likely never seeing her again after you leave, and for her (and you compassion) to be used as a weapon against you by him. If he sees you want her in your life, he WILL use this against you. 100% he will use this. He could very well tell the poor kid that you're leaving because you don't like her, to hurt you and to coerce you to stay. You HAVE to be prepared for this. You have NO legal rights on that child, sadly you cannot do anything to help her and you can't let your compassion and love for her keep you trapped with this vile man.
If you want to have her in your life after the divorce, you could see - after the divorce - if you can see her when she's at her grandmother's. Or you can try with the mother. But it might be best for her if you just end things cleanly so DSD is dragged into things as little as possible.