Hi lovely,
Unfortunately, I think sometimes being kind and caring is what puts us in these situations, we can be drawn to people who are struggling and we try to fix other peoples problems, never putting ourselves first. But for your own survival and your own sanity, you need to do what’s best for you.
I hope you can try to reconnect with your best friend and just know, you did nothing wrong. This isn’t your fault. He might get help at some point and I hope he does, but it’s not your battle and you need to live your own life filled with happiness and peace. I hope you get there x