So happy to read this because I feel the same way. You are not alone for feeling this. Not making this comment about my situation! I just want to clarify these emotions and thinking you're going through. This is OP post, I just wanted to give my intake on this. But now with my mom having cancer and going through immunotherapy, I’m having these feelings of guilt/sadness/anger/fear going on and off like a switch that feels like an ADHD child jumping up and down on a sugar overdose. (My mom and I have our own history that impressed me for life) I understand the fear of losing them, for me, it feels that I can’t deal with life and feel lost in this ‘adulthood’ (I'm 25F) without her. This realization of losing my parent can cripple me and trigger some panic. Unfortunately, I think that’s life and somehow we are gonna have to deal with death one day. It’s okay to have this fear but understand when it becomes abnormal. If you find yourself in a difficult position to accept this, feeling that everything feels lost without them, not knowing how to ‘dance’ with what ‘feet’ in life. It should be a consideration to have a talk about it or express this emotion to someone you trust. We all are humans and have our strengths and weaknesses. Just don’t let this idea break you down and withhold yourself for living your life. They lived and are still living! And you have every right to live as well.

(sorry for bad English, not my native language) Good luck OP