Hotchip- here are two articles that might help you process what happened.
https://www.bpdfamily.com/content/karpman-drama-triangleand another analogy story of the possible dynamics-
https://bpdfamily.com/message_board/index.php?topic=65164.0;allIn my situation, it was with a parent, so this is a long term relationship and one doesn't "divorce" a parent. Some adult children go no contact for their own emotional safety. In my situation, I didn't do that. It was BPD mother who would oscillate between being angry at me and then not - the "push pull" dynamics.
Although my BPD mother had mental health care- it wasn't effective with her for several reasons, - BPD was not well known at the time she started it, and also she herself could not process that anything that happened in a relationship had anything to do with her. She was in "victim" perspective- and any issues were someone else's fault. This also involved "projection" of aspects of themselves on to someone else. Without the ability to look inward, or motivation to work on that, that impacts the effectiveness of therapy.
So, if there was any idea of mental illness- although she might agree to attend therapy- she also would present us as the ones with the mental illness, and she did with me, several times. She did make some threats of self harm and we did call emergency when we were concerned. I agree with that advice but I'm focusing on the dynamics here.
We are human and have our own emotional capacity. There's also the "boy who cried wolf" phenomenon, with multiple threats a day.
Most of the time, I didn't react in anger at BPD mother. Regardless of the situation, I didn't want to be disrespectful to a parent. However, my father had passed away. I was grieving, emotional. I didn't have much tolerance for BPD mother's behavior at the time. I yelled at her and she reacted to that.
To parallel your situation- you had just lost a friend to the unthinkable. You were not in a good place emotionally- which would be expected. I think a non disordered person can understand that someone who has experienced a loss is having a hard time themselves, but someone in victim perspective doesn't. If you have been their emotional sounding board and now, you aren't doing that, they perceive it as you doing something wrong to them.
My BPD mother also reacted by telling people I was emotionally disturbed. In a way she wasn't wrong- I was upset- but for a normal reason. You were too, but where you assumed your partner would understand, he did not. If he was used to making a threat, or sharing your emotions, he still expected it, and when it didn't work, he had an extinction burst- "pushed the button" over and over again.
I think counseling is a great idea for anyone who has been in a relationship like this. With the victim perspective/projection/blame - it's hard to not blame yourself. I think it's fair to call behavior that is hurtful "abuse" even if the person doesn't intend it to be- when it has an emotional affect on the other person. Eventually the other person reacts to that. If someone is being physically hurt, they may react by fighting back, even if they aren't someone who usually does that.
In this situation, it seems you are in general, a caring person and your partner became dependent on your emotional caretaking. When you were in a situation where you needed someone to be empathetic to you, you assumed, like one normally would, that your partner would be empathetic to you as well. However, he couldn't be and his emotional needs continued.
You have a lot to process- the loss of a friend, and the ending of a relationship with a disordered person. That doesn't mean anything is "wrong" with you. It's a lot to process. Therapy can be a supportive situation for you to work through this. It's OK to post here too, but I think the one on one with someone also can help.