(((((LYIB)))))) You said it all with "a parent who is unwell."

That is a VERY sick parent. That is not your fault.
I know the feelings of being the child can be overwhelming.
But you know the TRUTH that the parent is sick. Very very sick.

You are doing great by reaching out with your words to others. You deserve to be heard. Sometimes we never can yell back (or hit back) the abusive parent.
But we have the NEED to be heard! You have a right to your voice and to defend the inner child of yours who should have been protected. That is now your job.