Which sentence do you find more natural?
Your last actions only prove me that you’re not worth my trust.
Your last actions only prove to me that you’re not worth my trust.
or maybe some other form like
Your last actions only confirm (my belief / me in the belief) that you’re not worth my trust.
The second sentence, ‘prove to me’, is more natural (and indeed correct where the first one is not). Prove is a verb so needs the to.
The ‘confirm my belief’ (me in the belief isn’t quite right) sentence is a bit formal.