BM,
The key for me when my mind drifts to dark negative places is my faith in God and his grace. I still struggle with sleepness nights and the negative what ifs but prayers and faith certainly help me through those times.
I'm not one to normally preach, but you asked.
I'm sure your boyfriend is getting the right care in the hospital and is where he needs to be right now. Use this time to take a little break for your self. I know this disease is very hard on the care givers too. Stay Strong!