If she doesn’t understand how you could come to reject Catholicism, perhaps it is true that she doesn’t know you and maybe never really did. You could explore her model of you with her and find out who she thinks you were and who she thinks you are now. What is it, specifically, that she is scared of? Does she have some rational fears or are they all irrational? For example, is she afraid that you’re going to go to Hell when you die (irrational fear) or is she afraid that your philosophical differences will strain the relationship (maybe more rational)?
If she doesn’t understand how you could come to reject Catholicism, perhaps it is true that she doesn’t know you and maybe never really did. You could explore her model of you with her and find out who she thinks you were and who she thinks you are now. What is it, specifically, that she is scared of? Does she have some rational fears or are they all irrational? For example, is she afraid that you’re going to go to Hell when you die (irrational fear) or is she afraid that your philosophical differences will strain the relationship (maybe more rational)?