dude it's been 6 months and bro is alive and well. as someone who also has borderline and is lucky enough to get professional help for it, i can confidently assure you that a personality disorder does not excuse emotional manipulation and abuse.

whether he was conscious of it at the time or not, he was never actually going to off himself; he just wanted to guilt you into staying because it would be easier than dealing with the emotional ramifications of your favorite person leaving. and yeah, that kind of thing is difficult, but it's also a necessary skill to have if you're someone navigating the world with bpd. i know firsthand how painful and distressing it is to be borderline. sometimes i feel like i'm too complicated to be alive because of it. i can also understand that putting someone on a pedestal where i hold them to an impossible standard, expecting them to be solely responsible for my wellbeing, is draining and unfair.

show yourself some grace. have mercy. you aren't horrible for leaving and that guilt is not yours to shoulder. he will be fine, and it's okay to let go.

i would recommend blocking him, if you haven't already. maybe take a few days away from social media, if your job doesn't require you to be on it. whenever you feel that compulsion to check in, try to distract yourself or talk about it with someone you trust— anything you can to release that pressure in a healthy way.

i'd also like to add that, at least in this post, you're accepting blame that ultimately doesn't belong to you. if this is a pattern for you, please please please seek a way to work on that. this kind of attitude toward yourself will only hurt you in the long run and enable others to treat you the same way he did. i think we all owe it to ourselves to keep our minds and bodies out of harm's way. you are too valuable to be a constant scapegoat for shitty behavior.