How can you help a depressed family member whose wife is having an affair and left but is stringing him along?

Unfortunately there isn't much you can do other than just being there for him. Your family member has to make their own decisions re his wife. If you get mixed up in this mess you are more than likely going to get blamed if the wife walks away for good. You don't know the whole story either, so I wouldn't get too stirred up about it being the wife's fault. I was married before at the age of 22. 3 1/2 years later I decided to leave my husband and file for divorce. I had not only his 2 brothers backing me on this decision, but many of our friends. My first husband was not only a mental/physical abuser to me, but cheated every chance he got. I'd put up with it quietly for 3 1/2 years and finally after his brothers talked to me about it I had the courage to leave. Strangely, when I left him, his brothers were fantastic to me and helped me through the process, but a good 1/2 of the friends my ex husband and I had were blaming me! I never once cheated on my ex husband. Your family member may not have cheated, but there could be other factors in the marriage between them so it's best to stay out of it. Of course he's going to feel somewhat depressed, but most of us get over it, move on and meet someone else. I was fortunate enough to meet my second husband several years later and we've now been married 34 years.