Disclaimer: For simplicity of quoting I won’t be quoting responses in my reply (unless necessary) as the OP was a quote on me. I’ll trust that people won’t go back and edit their posts to change their positions without acknowledging/conceding the point.
1a) objectifying forgiveness-
I see the angle you’re coming from. From a materialist perspective you’re treating forgiveness as an object; an entity of itself, not dependant on any outside influences/conditions. The problem as you’ll see in the definition below is that it’s an action not an object (read verb). In a causal universe action follows cause and is followed by a reaction. I hope we’re on the same page at this point, are we?
1b) defining forgiveness-
forgiveness [fəˈgɪvnɪs] n
1. the act of forgiving or the state of being forgiven
2. willingness to forgive
forgive [fəˈgɪv] vb -gives, -giving, -gave, -given
1. to cease to blame or hold resentment against (someone or something)
2. to grant pardon for (a mistake, wrongdoing, etc.)
3. (tr) to free or pardon (someone) from penalty
4. (tr) to free from the obligation of (a debt, payment, etc.)
I’ll assume nothing arguable from the dictionary quote?
What you describe is the act of releasing guilt, not forgiving. Would that be correct?
That is indeed one sided. I could see if you took pardon and used it like a noun you might reach your conclusion. As you can see above it is a verb, which is an action
1c) suitable analogy- I’ll use your analogy because it’s easier
Person X kills your kid and himself in a car accident and you (person Y) survive. I contend that Y cannot forgive X as they cannot communicate. Person Y can tell themselves that person X isn’t culpable. That would be completely internal to Y in this case and one sided. Absolution isn’t forgiveness though (unless you’re catholic

) it is a releasing therefore could be completely one sided. In that sense forgiveness would be one-sided as it releases (pardon/remit) one from culpability. As an action though it requires that it be directed to someone. As person X has no way to communicate that to person Y it would be one sided. However, I wouldn’t call that complete forgiveness because it wasn’t received by person Y.
2) I see we’re in agreement that fear of punishment or reward seeking should play no part in forgiveness or salvation.
3) Then how can you acknowledge complete forgiveness without acknowledging what/whom you’re asking/receiving? I know I’m forgiven in my heart because, through dogma, I’m told what are experiences/signs that I’ve been forgiven and I see them. I falsified them, so I feel they are true and indicative that I’m forgiven. You have no such claim to my knowledge.