I'm sorry you are dealing with so much. I believe dealing with our empathic abilities is a balance between the spiritual and the physical. When the physical is tired it is harder to keep the spiritual in check. It takes energy and mental awareness which illness uses up a lot of. However, as sad as you are I think it's great you are reaching out and I believe you will find some support here. I will give you my suggestions and hopefully something will sit right with you.
I used to have nightmares all the time, looking back some of those nightmares were spirits visiting me. I'm not entirely sure now they were evil or demonic but after watching movies and the odd horror when I was a child I personally associated ghosts with fear. I somehow found a way to block the spirit world entirely and I have kept that door very closed with unbelief for years. Just recently I have been drawn back to the empath world but being older and more mature I am trying to look at it from a different angle (I didn't know back then what I was so I had no way to deal with it). Since opening this door a little bit again I have had some encounters and have had to tell my subconscious not to react in fear but in curiosity and it seems to change the experience immediately.
I think you can set boundaries with the spirits - talk to them and let them know they can stay in the room but they cannot touch you. Speak out loud if you have to. I recall a story someone told me about an evangelist I can't remember his name but the story went something like he was visited by the devil in the night and he said "oh it's just you" and rolled over and went back to sleep. This story helped me tremendously with controlling my fear - they can't harm me physically and they won't spiritually if I don't let them. Boundaries - in the physical and spiritual.
Take care of your physical body, eat good food, exercise, take your vitamins, etc. The energy your physical body has will help you deal with the spiritual.
Find something to smile about at least once a day - being an old soul maybe you've lost your joy. Having seen and experienced so many things makes 'just being' exhausting. Look for things you can do and see that will make you smile or you will find interesting... find your joy.
Meditation is so important, talk to your sub conscience and tell it what you want to be aware of, what you want to recognize. Look into your Chakras as well - light and love. IT's all connected.
Anyway, I'm fairly new to this so just some ideas for you to look into - take what you feel resonates with your soul and leave the rest if it doesn't. I don't believe we were designed to be plagued. Wish you all the best.