Emotionally I just don't think he is capable, I honestly don't think this is malicious or a way of keeping me in my place, I think he just can't do it no matter how much he thinks he loves me. For whatever reason he cannot share his emotions.
Is that really the case? How did you meet him in the first place. Did he talk to you at all about his feelings. Has he ever been in the slightest bit open with you?
If not, then you may be right. And if, if, that is the case then he will not change and if you stay with him you will be controlled by his mood swings.
Remember what your dd said. She doesn't want to live like this. Whatever reason he gives you for his behaviour tell him this - tell him that you are worth more than that. His inability to communicate or open up emotionally, or just lack of will, it makes no difference, the result is the same
Ask him whether he thinks you deserve more than that. If he makes it all about him, he is still not 'getting' that you are just as important.
At the end of the day, I don't see that you have any choice now that your dd has told you how she feels. It's a clear choice between him and her. You have told us how he has nothing to do with her, yet he is her father figure. That is very damaging if you make her stay in this situation.
When you speak with him tonight, if you feel yourself unsure, just pop to the loo and mn on your phone. There will be someone around no doubt to help you stay strong.