Ready for depression

Me and Frank have been together for 8 months now. Yesterday he told me he's got to move out of his house to save money. He asked me to think about him moving in with me, if not, he'll be moving in with some friends in Rockmart about 30 minutes away. Why did he have to ask? Why when he's got the next two days off and we could have spent some nice time together in the beautiful weather? In this day and age most people would think I'm wrong. Most couples move in together without marriage. I don't fault those who do. It's just that after 11 years of separation from his wife he will not get a divorce. He's been in Georgia for 5 plus years and still has Illinois tags. He went to file his taxes and found out that if he files separately he'll owe money so now is trying to get in touch with his wife so he can file jointly with her. Something just isn't right. His life should be more situated. I'm not being a prude. I just don't think I'd be happy if we moved in together. Is there something wrong with me for not letting him move in with me? I'll have to tell him. He wants an answer in a few days. I'm scared. I'm going to lose him and I already know that the depression will hit and I can't stand it. Am I making the right decision? I don't know how I'll live when he's gone. I'll be all alone again.