Friend's Late Husband?

One of my friends lost her husband. He committed suicide, and she was a witness. So, she moved in with her brother (my boyfriend at the time).

Before she moved in with my boyfriend, his house seemed completely normal and neutral. Well, as soon as she moved some of her belongings into the house, I noticed a change.

I frequently went over there and would get there a little before my boyfriend sometimes, so he would have me just let myself in. One day I did, and I immediately heard some papers shuffling and boxes moving in the back bedroom. I assumed his sister was home and so I announced myself and apologized for letting myself in but got no answer.

I thought it was odd, but maybe she was busy or needed some alone time. So, I sat down in the living room, which has a clear view of the two bedroom doors.

A few minutes later, they both walk in the front door and she goes back to toss her stuff in the room and grab something from the other. No one was in either of them. Okay...odd.

I'm over there again and walk from the kitchen to the living room only to run into someone/something, but there is nothing visibly there? And I feel like someone is just watching us all evening.

This "being watched" feeling persists for a few weeks. Also, I started having serious asthma attacks while at their house, something I hadn't had for over 10 years. (Maybe a cleaning product or perfume the sister used?)

I go over another time and don't feel anything. But, I am having extreme difficulty breathing and have a strong urge to get out.

Boyfriend confides that his sister had been having awful nightmares (involving demons or something like that) and had been getting lots of bruises.

Her late husband's sister also came over to the house and while walking from kitchen to living room, exclaimed, "Something's here!" So they saged the house.

I go to leave because I feel like I'm just suffocating in there. (Maybe I'm allergic to the sage?) and get in my car only to feel "it" in my passenger seat. Whatever it was, it came home with me and just kind of moped around my place for a couple months. Whatever, nothing sinister there.

It never seemed aggressive or anything, just there and kind of dejected/displaced. It would never cross the threshold into my room, but would be near the doorway when I went to sleep. That kind of thing.

However, a little while after I noticed the mopey guy, I started to feel something else too. I would wake up to hot breathing right in my face (like a dog panting on you) and it was ANGRY. So damn angry. I then noticed stuff being moved around/not where I left it and thuds and dishes crashing at night. I can see my kitchen from my bed (studio) and obviously, there is nothing there. And no evidence of rodents or anything.

I also suddenly was scared to death of going in my basement. I'd never been scared of it before. All that's down there is a water heater and washer/dryer.

All-in-all, I slept less and less and started keeping the lights on all night. Eventually, I broke up with my boyfriend because it was just too weird and it all stopped. Just no more weirdness, no more feeling like I wasn't alone. Gone.

I don't really know what to make of it because I've never actually experienced anything like this before and more or less remained oblivious to and skeptical of this kind of thing.

I was never close to the husband who shot himself, so it seemed weird that he would come with me. (If it was him).

So, what just happened? Any ideas?