Hi woodlily

I remember your previous post quite well in which you mentioned your dad's extreme cruelty towards animals. He has exhibited quite some disturbing behaviors and I can totally see how that would unsettle you.
Great to see you here trying to learn new ways of communicating and interacting with your dad. You cannot control what he says and does, but you can work on your own behavior and responses.
We only want to validate the valid, and like
Harri said, we never want to validate the invalid. If possible, indeed try not te be invalidating. If you in the moment simply cannot find anything valid to validate, not saying anything is also an option, that can be perceived as invalidating yet that's still better than validating the invalid. Validation is a powerful communication technique, but there are also several other powerful ones which can be incorporated in your toolkit such as the already mentioned S.E.T. and don't J.A.D.E., but also for instance D.E.A.R.M.A.N. and B.I.F.F.
Since you explicitly mention 'perpetrator' and 'victim', it might hep for you to take a look at the so-called Karpman Drama Triangle:
Karpman observed that in conflict and drama, there is "good guy vs bad guy" thinking.
…...
Karpman defined three roles in the "transaction"; Persecutor, Rescuer (the one up positions) and Victim (one down position). Karpman placed these three roles on an inverted triangle and described them as being the three aspects, or faces of drama.
You can read more here:
Escaping Conflict and the Karpman Drama TriangleThe Board Parrot