How can I help my bf understand?

Hi, first time poster. I (27F) was diagnosed with BPD around 2 years ago after about 10 years of back and forth and switching between various mental health teams. It was extremely validating for me tbh - like everything made sense at last.

I was previously in a relationship for 7 years (aged 17-24) and with hindsight a lot of our issues stemmed from my BPD and his complete lack of understanding (although he knew I suffered badly from depression/anxiety and had childhood trauma).

I’m in a new, solid relationship coming up on two years. My BPD has been hectic recently and I’m really struggling. My partner (29M) is really trying to help me, to understand, and be supportive. I can barely understand my own head so how can I help him? TIA