I think what has helped me in part is understanding that this is a mental illness as you have quite rightly stated. It is helpful to be reminded of that as even with that knowledge we can quite often drift into the mindset of “was it something that I did?” type of thinking.
I think what I need is healing and support from others in this space. I’ve read that a discard is not the same as a typical breakup. This is something that I wouldn’t wish on my worst enemy and has been like a very bad dream.
A discard is way different because people don't break up like that (unless there's extreme abuse, sudden cheating, etc). It was the hardest thing to get through in my life as well and most would say the same thing here. Again, the problem comes back to trying to figure out what you did wrong, how you could fix this, etc. The longer you do that though, the worse you'll function because there's no clear answer other than, "He's mentally ill and made really bad choices."
Eventually you'll be mad at him. Then you'll realize you're better off without him. And eventually, months after that, you'll discover that he's sick and stuck in a lifetime of destructive patterns. I'm giving you the end-part up front...even though you can't process it yet...so it stays close to mind. He didn't do this to hurt you, he did it because he's mentally ill.
Let's play the "what if" game though. What if you didn't do all the things that led to the break-up? Would the relationship be perfect and happy ever after? Absolutely not, because what really happened is inside his mind. If what happened didn't happen, something else would have came up the next day, the next week, the next month, etc. and you'd end up in the same place you are now.
I'm sure you've made mistake like every other person on the planet, but you did nothing to deserve this and the "what ifs" are the worst thing you can do to yourself. We all did it and we were all depressed until we realized that we had to let it go.
I also need support around not wanting to rescue or wait for him to get better, and ‘charm me’. I am grieving the loss of the person he was not the person he is.
Getting better starts with realizing there's a problem. Then it requires getting into therapy, finding the right balance of meds (it's different for everyone), and actively working towards being a better person with a deeper understanding of yourself and how others perceive you. In other words, it's a process and BPDs are generally terrified of admitting there's a problem, so most never actively seek help (except in emergencies).
In short, you can't rescue him. Nobody can, not even the best psychiatrists in the country. The only person who can rescue him is him...he has to choose it and really work towards change. It takes years.
There is also the issue that all of his and his sons things are still at my home. I have sent a very boundaried, non emotional message telling him the date that he needs to return to collect these items but he has not read them yet.
This part is easy. Pack it up and put it to the side. If there's not enough room or you're sick of looking at it, send it to Goodwill or one of his family members. You did the responsible thing and extended grace. He's not taking it. So get rid of the stuff.
