My Ex is furious that I don't want to be friends, Is he right?

Im currently in the middle of a bad break-up of 18 months. we have lived together for the past year. We met in the midwest and lived there for 6 months, and then moved together to Los Angeles in July. Things went down hill and he decided to move home to the mid-west during thanksgiving. but for the past 3 days things were going really well untiL I found out that he slept with another person over halloween and called them babe and said that our relationship was ridiculous and that they were perfect and wanted to be with them. when I confronted him he said that he did it because he felt alone and that It had nothing to do with the last three days. Ultimately we decided it wasn't going to work. I feel like he's already over me, because I have been crying the past few days and he says "get over it" He said he wants to remain best friends, and I don't thing I'm strong enough to do that, I still love him. But he became enraged over the fact that I said that I didn't want him in my life. is he right? am i over reacting? he wants to spend his last 8 days here with me but it hurts to be around him....what do i do? please help