It's a horrible situation. And you need to get to the bottom of it.
Whatever the truth is, you need to support your daughter - either she has been abused (and for the second time), or she is unwell and she's calling for your attention or something similar (in which case she also needs support).
You don't need to think about your partner until everything's been resolved. You can place him in, so to speak, mental containment - you still don't know what has happened, you don't know what to think about him, so there is no need to rush into judgement either way.
I understand that you can't turn love on and off, but you don't have to do that right now. Just isolate him mentally - if he's guilty, you'll have evidence, and plenty of time to hate him. If he's not, you still have done the right thing - any adult in his right mind would understand that you need to be sure 100% when children are involved.
So what matters most here is that you find out what happened, and that you make it clear to your daughter that you will support her whatever happened.
I am very sorry you are going through this.