I think he's leaving me :(

So my fiancé told me that if he ever wasn't happy, he wouldn't be here. Last evening he told me through text message that he wasn't happy in our relationship. I have a feeling he is going to leave me. I'm not sure what to do, I don't think I'll ever find a guy like him who is so real and upfront, he's currently the only person I have to trust, he's my best friend, he's the only person I open up too. If I do t have him, I really honestly don't know how I'm going to make it.