Hi Kelsi

I think Cat explains it pretty well with this statement:
"It seems a lot of people with BPD feel threatened if they don’t feel the primacy of your love"
My exBPDh was incredibly triggered by any attention I paid to our son - let me clarify - his own biological child with me
Just prior to our divorce - he kept challenging me to prove that I loved him more than our son which obviously I could not do. He couldn't grasp that I could love two people equally but in different ways - all-or-nothing thinking in the extreme.
Also your sentence struck me:
"The horrible part is I never know what I’ve done to make him change his mood and turn into this monster I don’t know."
The answer is that you have done absolutely nothing. His moods are all about him, his internal feelings and likely have little or nothing to do with you other than you are a handy target of abuse for all that is not well with his world at a given moment.
This is a hard road...I've been there

Keep posting - this site saved me!
Warmly,
B