Hi love,
First of all try to just relax.
There's an old saying: "you can't change the wind, but you can adjust your sail."
We cannot control their behavior. It sounds like you've been here before.
That is, after all, one of the classic BPD behaviors: I love you/I hate you. Dr Jekyll/Mr Hyde. The back and forth is exhausting and the anxiety and panic the "breakups" produce is awful.
I totally understand. Been on that treadmill for 25 years.
Once they calm back down, you get that dopamine burst of "honeymoon" and "it's all okay," it was just an argument and we're "back to normal."
However, that is unlikely to last. It's awful, it's sad, and it's a very hard pill to swallow. But, it is a cycle.
You need to try to remember that you are yourself. You are an individual. It is so easy to get sucked into "my life depends on his well-being/happiness/acceptance/calmness/etc." that you completely forget that you were gifted with your OWN life as a human being and have incredible value! You have your own feelings, thoughts, dreams, etc. that should be nurtured and supported.
Try some self-love, self-acceptance, self-work, and do things FOR YOU that make you feel good. You will never be able to control him. You'll just be constantly doing "preemptive planning" and/or "damage control". Is that healthy or nourishing for YOUR life?
Do you have a therapist? I'd highly recommend you find one that you can talk to, share your feelings with and get the validation you need that YOU ARE AWESOME! They can teach you coping strategies, how to support your own needs, and work through the awful anxiety and stress of the cycles of BPD relationships.
I wish you well, love!
Keep posting and reading here, too. It helps a lot!