Welcome
though of course the circumstances for your arrival here ought to have been better ones. You will find that many here have "been there, experienced that". Please keep browsing and posting, there is so much collective wisdom to be found here.
One insight is that you can't fix serious issues such as BPD traits. You've been in a close relationship. The complication is that BPD is a disorder most evident in close relationships. Others who are on the periphery may from a distance notice something "off" but never be too impacted. Unlike how you are, as emotionally close as you have been.
People with BPD (pwBPD) typically can't or won't get past the emotional baggage of the relationship. So they can't or won't truly listen to you. Where you tried and failed all this time, just maybe an experienced professional, a therapist, not emotionally involved, might be able to provide meaningful therapy over time. Another problem is that pwBPD often have extreme Denial, Projections, Blaming and Blame Shifting. That's a huge hurdle to overcome.
That said, whether he will would ever seek therapy is up to him. On the other hand, you're reasonably normal, and you are probably willing to benefit from counseling, and of course benefit from our peer support here too.
