Can’t let go

My ex cheated on me, we were together for 4 years. We even lived together last year. I felt like everything was going perfect until he started getting more and more distant and no effort or attention was given to the relationship anymore. It’s been 6 months since we broke up now. But only 2 of those months was without a contact. I always reach out to him, because I get so sad and he was like a friend to me too. I feel so bonded, like a part of me is gone with him. I just want to let him go, I know he doesn’t appreciate me. But how do I close this chapter and look forward. How do I stop thinking or letting my self get disrespected time after time. I know I have to stop hurting my self by reaching out, but in a way I am already hurting just, alone now.