I need some advice that might have some effect on my fathers health and my parent's relationship.

I don't want to get too detailed but I can't think of anything else that might help. My father is getting sicker and less stable mentally. He has let his health go downhill over the past few years. I don't know if he is just malnourished or if he is fighting with some illness. He is paranoid in a way that I can relate to (whole other story). He is obsessing over my mother's actions. His trust was broken when she confessed to cheating, at least twice. Once twenty years ago, the other more recently.

They are trying to keep it together but it's like they're tiptoeing around each other all the time. My dad is extremely paranoid and snooping all the time. My mom is not one to take it when someone accuses her of things she didn't do. She blows up. Threatens to leave but comes back. They can't really seperate for a lot of complicated reasons.

My only plan is to keep hanging around. Try to make it feel like a family again. Both my brother and I have moved out.

At this point I just want my dad to get healthy again but I can't fix it for them. Don't know what to do. Please if anyone can give me some advice.