You can't get back someone who doesn't want to be back. He told you, explicitly. how he doesn't love you anymore & that he had been lying to himself when he expressed the opposite to you. He also keeps showing you that he has moved on. Let him go.

And whoever told you to be patient, sit and wait for him e.g. "I keep being told he will hit rock bottom at some point and realise he is making a mistake, and that I need to be patient": this is rubbish advice. You should never put your life on hold for someone who has moved on and keeps telling you they don't love you. Accept what he keeps telling you - it is over.