I wanted to get a sense from people, given their experience and perhaps even studies on abuse, whether it's better to stand up for oneself (after an abusive relationship) and confront the person on all their abuse, their lies and BS, OR whether it's better to go NO CONTACT and ignore them completely IF they contact you again?

This is a hypothetical situation.

I am wondering primarily for the sake of one's mental health and feelings of self-worth and self-respect.

From Psychology Today (when facing abuse):

Confront abuse effectively.

Allowing abuse damages your self-esteem. Thus, it’s important to confront it. That doesn’t mean to fight and argue. It means standing your ground and speaking up for yourself clearly and calmly, and having boundaries to protect your mind, emotions, and body.