falsely accused of damaging a phone

Because I went to confront my fiance ( we have 2 kids together and are planning our marriage this December) she reported me to the police and accused me of threatening her life and damaging her already damaged phone. As a result, I was detained and asked to buy a new iPhone X for her. firstly, I admit I messed up in going to confront her and I didn't lay my hands on her. But she accused me that the same phone she showed me was spoilt before I even touched it and extorting another one from me I want to fight her legally for that. I want to know how many percent can I get victory on this case and the cost.