I personally understand the feelings behind the need to off someone. The feelings of frustration for connection with people who aren't skilled in empathy (reciprocal connection in feeling heard and understood) is a formula for exponential frustration. It ends when you kill the need within yourself to bang your head against the same brick wall. Therapy gave me a new skillset of coping tools, but Thom Bond's Compassion Course sealed the deal because the course taught me to first listen to myself, feel my feelings because they guide me to my needs and then speak respectfully in wanting to know if the other person wants to connect differently in sharing mutual needs. Yes or no. Win/win either way. New tools brought into the mix or walk away peacefully. Your folks are old, perhaps stuck in their ways and may feel anxiety from the toxic shrapnel. I learned to watch over their care as Mom's adult child AND also claim my adult autonomy without becoming enmeshed in her drama. Very liberating. Especially when she went into a care home. She died at age 90 in her sleep, and I felt relieved without shedding a tear.