Imam Bin Uthaymeen explained that you shouldn't forgive if the harm will continue. Does this apply to parents as well?

The principle Imam Ibn Uthaymin raḥimahullāh mentioned is a general one: pardoning a wrongdoer is better only when it brings about reform, because Allah made that a condition when He said, the meaning of which is: "Whoever pardons and makes reconciliation, his reward is with Allah" (Surah Ash-Shura, ayah 40). So if pardoning would only let the wrongdoer continue harming, then taking one's right is better. As for parents specifically, their case has its own weight in the Shariʿah, so ask about your exact situation before applying this to them.