Nettie, it sounds like he has depression or midlife crisis that is not necessarily your fault - but he is trying to make you feel as if you are to blame. if you can afford to see an individual counsellor, I highly recommend it. the purpose of the counselling is to give you encouragement so you will not feel guilty for things that are *not* your fault.
if you can't afford counselling, post here with more details about your marriage, history, etc, and we will help you with encouragement and suggestions.