How Did You Finally Connect Reality with Leftover Feelings?

I’ve been no contact over a month from my BPD, highly narcissistic, substance abusing ex. I am really struggling with accepting reality/denial that he will really never be the one.

The last 1.5 years we were together on/off because he was spiraling with drugs to cope with business ownership stress, unresolved childhood trauma, untreated BPD, etc. He is an extremely intelligent, hard working, high functioning alcoholic and addict. His drugs of choice are ketamine and some cocaine. He will swear up and down that K is his “medicine” and that he only used it as a “tool”, “a life cheat code”, “to combat boredom”, “to keep working longer”, “to not be so reactive”, etc. All the things a person with a severe substance abuse issue says.

I recognized that he had deep issues almost immediately, but love him deeply and did the best I could to support him. The combination of everything he was doing resulted in him having many episodes of mania and a few bad episodes of psychosis. He once pulled a gun on the neighbor because he became convinced the neighbor was a murderer and he wanted to “show the neighbor not to mess with him”. Our relationship was almost constant chaos from the push/pull of BPD and his addiction cycle. i had to draw really hard boundaries, like kicking him out of our house, and was constantly in fight/flight.

After a bad episode, he would come down over the next couple days and it would be like nothing ever happened. We would have seemingly deep, honest conversations about how he didn’t want to live life the way he was anymore, what we wanted in life and how to take it on together, and how we could break the cycle. He would always say that he knew what he needed to do to be the man he wants to be and the man I deserve. It of course never stuck more than 3 weeks - he would always go back to getting drunk/high and creating chaos.

MY question is - how do I finally let go? I am in therapy, I’ve never had substance abuse issues, I’m physically healthy. I have anxiety, but I am intelligent and stable, a pretty successful woman. I am struggling badly with connecting rational understanding/pretty clear view of reality with how I feel.

It’s like knowledge that his mental health and addiction issues were treatable while also knowing the reality is that he doesn’t want treatment. I am struggling with loving him so deeply and knowing he is fully capable but also having to accept that he won’t stop hurting me. The more love of any kind that I offered him, the worse things got. It’s the hope that he will one day do what he says he wants to I am addicted to. How do I let go?