Boyfriend has horrible nightmares.

So my boyfriend has had nightmares since I first met him but they are getting out of control, he has demonic dreams, of houses that were haunted that he lived in, he has dreams of the devil, and evil. He has dreams of walking into a room and seeing himself hanging. He has dreams of him killing himself and death, he has dreams of me also cheating on him all the time, it's getting so bad hes waking in panic an cant sleep anymore and will wait until the suns up to sleep again. Hes stubborn and wont go to the doctor he wont take pills. He said to me today maybe I'm depressed? And that's why I dream of dying? But I dont know why I dream of demonic stuff.

It's scary and I'm really worried about him, hes 25 this year, he lost someone really close to him to suicide a couple of years ago now well it will be 2 years in October.

I'm assuming that probably plays a part. But it's been years but it's just getting worse!

What can I do? :(