WHAT SHOULD I DO? I HAVE A DISABLE SON AND MY WIFE ASKING FOR DIVORCE.?

What should I do? My wife and I been married for 15 years with a 11 year old son who is disable, injured at birth, he was diagnosed with cerebral palsy we sued and recently settle for 7.9 million which is still in progress now my wife wants a divorce. It all started back in april of 2005 when her brother,wife and their daughter came to live with us since then my wife never been the same, she stop sleeping with me, first it was days then it became weeks and now months. I was’nt taking that serious at first I would feel it’s because of all the stress with my son and all but the constant nagging became regular like every day, I like to think she’s not cheating on me because I never did, it’s only the constant fighting she would start on me if my mother, sister or nieces or any of family call me and say something like don’t worry every will be ok that’s a big quarrel with her and things like I don’t treat her brothers and her sister good enought how can I when sometime’s their family of 3 or 5 would stay with us for months and her brother, wife and kid was with us for all most 5 month’s and not working. I would have to do 2 shift’s some time’s just to make end’s meet now she’s turning that again’s me like where I use to be that time out there I swear on my son I never cheated on my wife and would acused me more than cheating out there but with my brother’s wife and my niece who lost her father just this past January ,it hurt’s a lot to think of something like that, I can’t take it anymore today she start fighting with my sister and now ask for a divorce. Am I a bad father if I should do that what she want’s and left my disable son and leave? Please advise me I don’t want to leave but she is screaming on top of lung’s telling me toleave her alone and get out my house. Or I should get some leagal help?