Hi MiloKay26 and a warm
A lot of us have had a similar journey to you -- there's a person in our life with confusing behavior, we look for resources and understanding and find books like Stop Walking on Eggshells, we get pointed to the message boards here, and we find a community of others who have also been confused and started learning more about PDs (personality disorders). I think for me, I might have searched online for something like "entitled mothers" (my husband's kids' mom has many BPD type traits) and after a few twists and turns, ended up here.
Many PDs share similar features, such as a distorted sense of self (exaggerated/inflated in NPD, weak/absent in BPD), lack of insight into impact of behaviors on relationships, blaming, emotional neediness, etc. Sometimes it matters what PD it is, and sometimes it really doesn't.
Labels/diagnoses can have benefits and drawbacks: a label can help guide our learning so that we aren't spread so thin in trying to understand behaviors, a label can also help us not feel so alone and find community, and a label can focus our efforts onto what's effective for interacting with a PD (versus general relationship advice). Some persons with PDs find relief when given an official diagnosis from a professional (though not all do).
Labels can have downsides, too -- we can get caught up in "I need to know exactly what it is" instead of knowing that whatever is going on, whether diagnosable or not, it's the behaviors/traits that are the issue, not the label, and so we are empowered to build new effective skills based on behaviors, no matter what is going on with the other person. Some pwPDs (persons with PDs) find a label or diagnosis stigmatizing, especially when told by a loved one versus a professional.
While it's hard to say exactly what your ex/partner was dealing with, what's true is that those traits and behaviors had a big impact on you.
To be in a relationship (of any kind -- friend, family member, romantic partner, even coworker) with a pwBPD (person with BPD) and to have it be effective and as healthy as is possible,
takes a great deal of work... on our end. We need to work on our own sense of self,
our own limitations, values, and boundaries, and our own black-belt level communication skills, in order to keep it healthy.
It's good to hear you have a therapist supporting you right now. Your T sounds pretty wise about PDs -- so often, when pwBPD are in our life, we find ourselves turning the spotlight on them: what are they doing, what are they thinking, how can I get them to heal, how can I get them to change, how can I support and do things for them.
The real questions might actually be -- how can I work on myself? What can I focus on in my own life, to be as healthy as possible, so that when I'm relating to my pwBPD, I don't lose myself in
enabling behavior? How can I improve my communication so that I can be clear and compassionate without being rigid or passive? What has happened in my life that might draw me towards wanting to "help" or "save" or "rescue" or "not abandon" my pwBPD?
Relationships with pwBPD aren't impossible, though they will likely look and feel different from "generally normal" relationships.
I think you're doing good work with your T to understand what you'd want out of a friendship or relationship with your pwPD.
Maybe you can look at those questions about yourself, and learn more about PDs here, for a bit, and see what insight those paths give you, as you figure out how to make wise decisions about this relationship. If there's no rush or deadline, gifting yourself time to think, learn, and grow, could bring you some clarity in this confusing situation.
We'll be here for you along the way...
kells76