What do i do after my boyfriend leaves me for his boss's daughter?

I was with my boyfriend for 4 years. We are both 27 years old. We went through so much together. I truly love him and thought he was the one for me. We shared so many memories together. He was the sweetest guy. One time after watching the movie, notebook, and telling him how much I loved that movie and it was one of my favorites, he bought the movie soundtrack cd and gave it to me as a gift. We listened to it over and over until the cd started to skip. I got him a keychain when we first started dating and I couldn't afford something expensive. He said it was the best thing and used the keychain for all the 4 years. He always bought my favorite chocolate every month when it was time for my monthly period to start because he knew I craved chocolates during that time. When he got into a car accident, I was there for him every single day,helping him out while he was on crutches. He was busy studying to become a lawyer and I would study with him quietly. I really thought he was my soulmate. He became a lawyer and he got hired at a top law firm. He was busy and had less time for me. I tried to understand because he was busy with his work. He was doing well in his job and he mentioned there was going to be a celebration/party for him thrown by his firm for winning a top trial. I marked the date on my calendar. A few weeks later when it was time for the celebration, I tried to get in touch with him to go together but I couldn't get through. I decided to go by myself and I would meet him there thinking maybe his phone wasn't working. His boss was giving a speech and my boyfriend went up to give a speech. I saw him look at me and I just smiled. I was so happy for him. He started to thank people and he continued to say how one person was always there for him, how that person makes him so happy, etc. I thought he was talking about me, but he called someone else's name. I just stood there, while another girl went up to him. I just stared at him, speechless. He saw me, he knew I was there. I found out she was his boss's daughter. I just walked out and cried in my car. I was just...lifeless for a few days. I went to get some fresh air at my favorite place, a place where I just go sometimes when I'm feeling down, a place where my boyfriend knows about. I was just sitting down at the bench when someone sits next to me and it was my boyfriend. I just looked at him and I couldn't say anything. I just cried. I walked away again without saying anything. I threw out everything he gave me, burned all pictures, deleted everything. It's been 2 weeks since and I'm just having a hard time right now. I don't know what to do. I just don't know what to do..