Why is my wife so dern bitter and hateful:?

My wife and I are approaching our 2yr anniversery in two weeks. We have 13mo old GGB Triplets, which I know are an enormous load. I work 65-75hrs a week and make 150K. Although my career keeps me away a lot, I do all that I can to help out with our children whle I am at home (every night as I don't travel). She has weekly maid service and I also have hired several "helpers" for her to loosen the load. She has gone through four helpers that she initially picked because she couldn't get along with them. All she does is critizize my every move. She has had a lot of medical issues, and is taking lots of medications. Hydrocodone, well golly, I cant list them all, but I think it's the Hydrocodone that makes her so bitter. She threatens divorce very frequently and does not communicate to me what she need/wants. I really am at a loss. Our life has ended. She sleeps on the couch. She rarely answers my phone calls while I'm at work, and when she does, it's "poor me" and I am the source of all of her problems. Her brother, who lives 3000 miles from us, and I have spent an entire 12-15 hours with my entire life tells her today that I am resentful that we have triplets. I really want to kick his ***. I mean, gee whiz. Why do I leave home for 13 hours a day to make a paycheck to feed/insure/clothe our entire family if I'm resentful of it. I am honestly becoming resentful that I am married to her. I am truly at a loss. I am so proud of my children. They have certainly added joy and happiness to my life. I think that she is the one that is resentful. When I met her, she was 29, recently divorced and living with her mother. Now, she is a stay at home mom, (not suggesting that's a vacation with triplets), but give me a break. I don't know what she wants from me. I honestly feel that I am a great father and my friends don't know how I handle this. She is extremely over-opinionated and critical of me. She always seems to start a fight with me at any given chance. I try to hold my cool, but it is very difficult to endure her grouchiness and hateful sneers she gives me everyday. She posts to her triplet connection website that she does not like me anymore and that she is unsure we can "weather" this. I'm the type to take the punishment my entire life before calling it quits. I want to work it out. She may not want to by her actions it seems apparant. I want her to be happy, I truly do. I realize that I am not resposible for her happiness. I need some suggestions to help her be happy, content and grateful that she's go the most beautiful babies in the world. Her goal was to become a MD, which didnt' work out for her because she didn't put the effort into her studies. Now, with the triplets, I truly believe that she has sacrificed her life plan to become a dr and now she's bitter. UGGG....I am so unhappy. What to do?