My ex-boyfriend is with someone new, and it hurts

I just got out of a two year relationship. I broke up with my boyfriend because he wasn't showing any affection at all. He was talking to other women and lying about it. It pushed me away and hurt me, but I'm still in love with him. A couple days after our breakup, he was talking to someone new. He told me he wasn't sure if he loved me. I cried for several days, lost my appetite, and couldn't sleep. Our whole relationship was only us. We didn't have friends. It was me and him against the world. We didn't talk to anyone else because we only wanted to talk to each other. We hung out constantly and Skyped to sleep every single night. Then, when I cut myself, we talked on Skype. He cried and told me "I'm still in love with you, I never stopped loving you," and I cried tears of joy. I asked multiple times if he loved me and asked to make sure he wasn't just saying that because of me being so depressed. He promised and assured me he loved me. He came over after that, and we had sex because he wanted to. He went the home that night and told me he didn't love me, and he lied because he was scared. He told me I wasn't attractive, I wasn't beautiful to him, and that I changed. He also told me he was 100% sure he'd never love me again. I'm still in love with him. Why do I love him? How do I stop? Just knowing that someone else is with him hurts me. That I wasn't good enough and that I'm no longer beautiful hurts me. I think I need a therapist, but don't know if I should.