。
The speaker made us deeply realize the truth.
Literal
Speaker [topic-は] truth [object-を] us [to-に] deeply [adverbial-と] made-realize.
しみじみと is a 擬態語 (state mimetic) meaning 'deeply, keenly, with heartfelt emotion' — it colors the realization as profound and personal. 悟らせた is the causative of 悟る ('to realize, become enlightened'). われわれ is a formal first-person plural.