Let go or Hold On?

How can you let go of someone you love for your entire life, because you're not entirely happy anymore. But still, you love him dearest and you  don't know if you can live without him. 
Though you felt like your afraid that the more time you give your marriage a chance, the more hate will harbour. And what if by the time you had the courage to leave him, there's no love left but pure hatred. 
Not making sense here but definitely hurting.