Hello dreamer101,
LDRs can be tough enough between two healthy people. They can be very tough when one partner is BPD, or has BPD traits. From what you wrote, it sounds like you concluded he has BPD. That's ok, as a lot of us arrived here the same way, as did I.
Aside from the obvious emotional dysregulations, a core trait of the disorder is shame. My Ex hated herself that she couldn't control her emotions sometimes. We do have members here who are able to talk about BPD with their partners, but it's rare. Even those who are diagnosed can fight the Dx, even denying it.
What's key is working upon communication on our side. Often, we unknowingly trigger the disorder when we're just trying to make sense of things or help. Take a look at the lessons to the right of this board, particularly Lesson 3, which has communication techniques developed by leading experts in dealing with the disorder.
"Testing" you like he did is a dysfunctional coping mechanism based upon his core fear of abandonment. Validating his feelings is a start. Take a look:
Communication using validation. What it is; how to do itTurkish