Looking for advice on how to cope with this

So I was in a relationship with the father of my baby for over 4 years. We broke this last fall. We decided we both needed space and time. So we both started talking to other people. However we continued to talk and hangout. Regardless of the space I still loved him. But he then told me he had met this girl he really like. So I decided to keep my distance then. A few weeks went by and I discovered I was pregnant. I was nervous to tell him I wasn't sure how he would react to the news. To my surprise he was excited he always wanted to be a dad and we had always talked about having kids in the future. We talked things through and decided we would give it another try for us and our baby. Things went back to how they were but he was more loving and caring then before. We told our families the news and we made plans that I would move in with him. I was excited to start our own little family. Time went by and things were going well or so I thought until last week. Last Wednesday he had came to visit and had this look in his face I asked what was wrong. He said he was tired of this and couldn't do it anymore. He confessed he had feelings for that one girl he had met and that he didn't love me or felt anything for me at all anymore. I was heartbroken I was confused I thought things were good I didn't understand why he had pretending to be happy? I was devastated I begged him to stay to give us another chance that the baby and me needed him more then ever. He said no, he told me to move on that he had and had found someone else that made him happy. He left us I'm currently 12 weeks pregnant. This past week has been the hardest time of my life. I never expected that from him I really thought he was going to be there for the baby and me no matter but I was wrong. I'm having such a hard time dealing with this pain. I would like to ask any mothers out there if they have any advice on how to move on from a situation like this?