Lying

I have a question and I do intend on asking my Priest about this.
Say you commit a Mortal sin against someone.You feel deep remose, you repent, you do go to Confession and start trying to do well.
Say the person you sinned against asks you about the situation it in the future, is it then a Mortal sin to lie? The Mortal sin has been forgiven by God and you did you penance and have moved forward with doing good. The reason you lie to this person is because they will harm or kill the other person it is involving, and you know this as truth as the person has threatened it before in a what-if conversation.
Does the fact that you already confessed about the Mortal sin change the severity with the lying? I know the reason to save someone does not matter.
Let me know if you need clarification.

ETA telling this forgiven Mortal sin would in turn cause another Mortal sin for the person who already confessed to the the Mortal sin that was having to be lied about (apart from the violence it may cause towards someone else). Despite this person now being a very devout Catholic and good Christian.

If you believe you must lie to prevent a person from harming or murdering someone, this is a clear indication you must cease all further contact with this person. This is an indicator the person in question is dangerous and unstable.

You don’t lie. What you do is you get away from this person and report this threat to the police. This is not normal behaviour.

Some people say this out of rage so it is hard to ever tell but specifically for any situation in where a Mortal sin was commited, reprented and confessed and brought up again what do you do? Even after God’s forgiveness and your repentence are you still tied to these sins and having to continue to live them over and over? You can’t move past if you are still reliving them.I’m not even sure how to ask this or how to explain what I mean.

the person making the threats doesn’t have a right to the truth. I wouldn’t regard misleading that person as telling lie.

F/

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