Husband wants to separate, I don't.?

I need advice. My husband and I have been married for 10 years. I'm 35 and he's 42. We have a 10 year old daughter. We have been arguing a lot for the past few months... and we have both threatened separation/divorce more than once. Last Saturday, we had another argument, and he said, "Maybe I don't want to work things out. Maybe I want a separation." Later, online, he sent me a message telling me that he needed space/time to figure things out. Whether or not he was still in love with me and if this is what he wants for the rest of his life. I realize that we are having problems, but I didn't know he was unsure of his feelings about me. He wants me to leave... but I don't want the separation. I don't want to lose him or leave my daughter. He has made it clear that I cannot take her. I also don't have a job, I'm a housewife, so I can't afford to rent a place at the moment. He says that this is only temporary... 2 months or so. But, I am heartbroken and worried. I love him very much and I want to do everything I can to make our marriage work. Not only for us, but for our daughter. I have tried talking to him about my feelings, but he won't change his mind. I trust him... I don't think he's cheating. He has been dealing with mid-life crisis, so could this be why he is confused about his feelings for me? I mean... that mixed with the arguing? I am so confused, sad, worried, angry... I really can't explain it. He keeps telling me not to worry, but how can I not if he is unsure of his feelings? We separated for 3 months back in 2008, but it was my decision... he said it helped last time, so there is a chance it might this time as well. What should I do? I can't deal with the fact that I might have to leave my daughter.