Why won't he talk to me?

I've been involved with this guy for 7 years. Fell madly in love with him. Problem: he's separated but not divorced. I could never bring myself to give him the ultimatum of "choose me or lose me" because I feared he would totally cut me off. Well, my fear has come to light. About a month ago I told him I was going to give him some space to straighten things out in his life. We continued to talk that week after and things seemed fine. Then one day he just stopped talking to me. I mean, like he became somone I don't even know. He is cold - he won't answer my calls nor will he return my msgs. Something he PROMISED no matter what he would never do. I'm hurt, confused.. and don't understand. He works 2 jobs and is very stressed out - that much I know. I also know he's not involved with anyone else. So, why freeze me out? I still love him deeply and don't know what to do nor do I understand what's going on. I feel lost!!