Need "relationship" advice please.

My husband passed away in February. I started seeing this guy who was a friend that I met through another friend. So...this guy I was seeing was living with me at the time because he had nowhere else to go and I'm not the kind of person to let my friends live out on the street. Anyways, after he moved in was when we started dating. We were together for about 3 months. Then he went to go see the friend who introduced us for a week (he was only supposed to be gone for 2 days). When he finally came home, he told me that he cheated on me and was moving out cuz he "couldn't live with me knowing how much he hurt me." So that was back in July. We've managed to stay friends throughout all this crap. Then on Friday, he and our friend that introduced us came over and we hung out for the weekend. My ex asked me back out and said that what he did was the biggest mistake of his life. So..I thought I'd give him another chance. But then today, he tells me that it was decided last night that in a month and a half, he's going to have to move to California for 6 years for work. I don't know what to do. He says he doesn't expect me to wait for him so now, after being back together for 4 days, he thinks we should go back to being friends. What should I do?