Please help me. I just need to leave

How do I get the strength to leave someone that I love more than anything. He’s my best friend. My family. But I know we’re not supposed to be together. I’m not happy anymore. Too much has gone wrong. And the problem is that if I’m not with him, im going to lose him all together and im not ready for that. I’m really at the point where I want to pack up my things and move to a whole different city. I wouldn’t do that cause I have a whole life here but I just feel trapped. Can someone please help me. I’ve prayed and prayed and idk how to make myself emotionally strong enough to leave. Any tips??