Hi buterfly
Im sorry to hear that your r/s has become unbearable.
I know how you feel, having only broken up with my pwBPD last weekend. I was asking the same questions then as to how to actually go about doing it, once I had made the decision that it was necessary for my sanity and safety, as well as genuinely feeling he has a better chance of improving without me due to being an almost constant trigger for him.
The advice I received from others here was that only I could know what was best for me, what I felt was right to say, and what I felt was the best way to go about it. Obviously the same applies for you. You have to decide what you feel comfortable with. And safety is important too and by that I mean that if you think your safety would be in danger by telling him in person, then maybe leaving a note is best. I know it's not the way most of us would like to deliver that kind of message, but as BPD is involved then things are a bit different.
I live in a different country to you so I'm afraid I can't help you with your questions regarding the home and finances etc.
Have you thought about where you would go? Right before week split up I was trying to get a plan straight in my head about what to do, and was going to ask a friend if i could stay with her for a bit. She had previously offered to have me stay, knowing how difficult things were. But as it turned out, my BPDexbf had a nasty bout of dysregulation which led to me calling the police and then his parents picked him up to stay with them. I broke up with him a couple of days after, feeling it was the only option available really. I couldn't take anymore of the walking on egg shells, rage, lack of emotional support... . well you know the story!
So although I didn't have to leave myself, I would recommend that you plan what you're going to do as much as you can. Being prepared will make it a bit easier.
But it sounds like that's what you're doing, by asking questions here
