BardIf you go by character concept rather than exact plan: Bard or sorcerer.

Since bard and sorcerers rely on innate ability rather than actual training it meshes well with the idea that your character is mistaken about their skill with divination spells. They can use spells, and their non-divination spells work as expected. But when they think they are casting divination spells they actually cast another spell like minor illusion or silent image which shows what they believe to be true rather than what actually is true.

On top of that, spells like friends and charm person let the character know they were being influenced after the spell ends. That could explain some of the fights that Roland ended up in. He charmed a person to get their aid and when it wore off they attacked him so he assumes they were actually in league with the vampires.