Partner broke up because of my undiagnosed BPD

Hi, I guess I’m just looking for kind words and advice. My partner of 3 years has broken up with me because of my ‘anger and rage outbursts’. I always knew something was wrong with me and I tried so hard to find out what it is… recently I have been on D*** for about 2 months and the outbursts before going on this medication were quite harmless. During the last 2 months being on this medication I have noticed the silliest things triggered me and I went into a full on rage phase calling my partner nasty, harmful words which I have instantly regretted right after. It was almost like I had no control of what I said, I felt so much guilt and regret right after and apologised and noticed all the things I’ve said to him are a projection of what I believe about myself and not him. He has broken up because he couldn’t take it anymore and he is struggling with depression and ptsd himself. I don’t know how I am ever able to forgive myself for that. We were planning on starting a family soon as well. I have tried to explain to him that this is not my true self and something is wrong with me, and I need help and treatment. I hate any form of abuse and are usually a genuine, kind and caring soul. He did not believe me as I have not had a formal diagnosis yet. I did not actively choose this behaviour and I felt misunderstood my whole life. I am just heartbroken losing my person over something I have so little control over and looking for some guidance and kind words please. 😢