Confusion of the heart and mind

Have you ever trusted someone completely, and thought you knew well, only to have them change, turn into someone else entirely, and treat your heart like a punching bag? You take blow after blow, but you stay, because you still kind of love that person. But eventually you turn away, figuring you've lost that person forever, and to simply stop trying to find what no longer is there. But after you've built those walls, to shield your heart from the pain, you catch a glimpse of the person you use to know, love and trust. Your heart want to open right back up again, to believe that that person is back and will stay, that they'll never hurt you again. But at the same time, your mind is telling you to stop, to stay walk away and not look back. Because you just know it will happen again. That you'll get your hopes up, only to have your heart mangled once again. But at the same time, you know you need to trust people, to not live a life alone, of fear and caution. But what do you listen to, what do you do? Which way do you go? Its very confusing...