My boyfriend left me after he became a successful lawyer. How do I move on?

[SAD]

My boyfriend, now ex-bf and I have been together for 4 years. We went through a lot together, and I was there for him supporting him no matter what. He got into an accident 2 years ago and had to be in the hospital for 5months. I was there every single day helping him out. I was there for him through every single little thing. I supported him while he was a law student, packing him lunch and bringing it to his work whenever I was free from work and school etc. However, he changed after he became a lawyer for a very successful firm. He's doing quite well in his job. He just stopped caring about me, like he dropped me. It wasn't because he was busy, I would understand of course if it was that reason. He cheated on me with his boss's daughter. I stayed with him. My friend works in the same firm as he does and there was a big company party. My boyfriend never invited me, but my friend invited me so I went. I wanted to see my boyfriend because I never got any closure. What was shocking was my boyfriend won an award and when he was giving his speech, he was thanking everyone, and he was saying how he was thankful to this one particular person how she was with him through EVERYTHING. He was looking at me and I thought he was talking about me, but he mentions that other woman's name. I just stare at him and he just stares at me while that woman is going up to him to give him a hug. I turn away and just walk away and leave. I never heard from him. It's been about a month since that night and I'm trying everything that I can to move on, trying to re-live my life, but I can't bear the pain sometimes. What can I do?