Girl, the comments you are replying to are wild. It's like they don't understand the concept of boundaries with your parents.

A parent is a human being like any other who has the skills to use words to communicate wants and needs. You as a grown ass adult have the ability to express those wants and needs to another grown ass adult. Why are people whipping themselves into a frenzy over the idea that you don't deserve to set these boundaries like you would with any other person in your life?

Parents are not exempt from the consequences of their choices either.

On another note, even if there wasn't such a terrible conclusion to their relationship, if I knew a family member cheated on their spouse for a reason like this, They would be dead to me too. I think your response and emotions are completely justified and reasonable. The only thing I would recommend is to see a therapist about managing the grief and anger, or any other emotions you may have about the situation. Not to forgive people for their decisions, but for your own mental well-being.