How do I stop things going back to the way they were?

[Ridethestorm]

I recently split with my husband of almost 30 years for what I thought was emotional abuse. It's always been like living with two different people, but for a few years before the split it was only one side I ever saw. When he left, he went straight to GP and got therapy and meds, everyone told me how different and calm he was. I was bombarded with texts telling me how much he loved me and didn't realize what he was doing to me. He didn't realise he was scarring me, took accountability for everything and said he was a changed man. At this point he was diagnosed with borderline personality disorder.
After a few months I decided I had to see for myself and give it one last shot. I'd always seen the vulnerable little boy underneath it all and thought things could change.
As soon as he got through the door he stopped his meds and twists everything so it's actually all my fault. Our adult son is no longer speaking to him because of the things he's done and said. I really want to help him, I want for this to work out cos this time is the final chance but once again it feels like I'm living with my worst enemy. Every word has contempt behind it. Also, his family back home totally, they're all manipulative, argumentative and abusive to their own partners. How do I stop this dynamic before it gets too ingrained again?

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