Hopeless, helpless, tired, DONE

I am new to this forum, just registered today.  My husband is 53 years old, non smoker, healthy except for slightly overweight, and was diagnosed with esophageal cancer in July 2014 after severe acid reflux and barretts esophagus.  He had surgery in August 2014 to remove a stage 3 tumor.  My husband is career law enforcement, most recently in the field of corrections.  This has completely destroyed him physically and emotionally.  I don't even know who he is anymore.  He went from a strong, no excuses kind of person to a physically and mentally weak person, he complains day in and day out and spends endless time feeling sorry for himself.  I don't want to sound unsympahetic, but I am his only caregiver, we have no family support here in Texas and I am alone in this.  He has melt downs and threatens suicide.  He calls me names and picks fights with me.  His attitude goes against everything he believed in before.  I have my own health issues.  I had gastric bypass in 2001 and have endured 11 surgeries since then to fix issues.  I becamed addicted to precription meds during that time but have almost 5 years of sobriety now.  This is testing me to my limits.  I have done everything in my power to help him including refering him to my therapist who he sees every 2 weeks.  He doesn't listen to doctors, me, or friends.  He has been told that attitude is very important but he has always been somewhat of a negative person because of the terrible things he has seen in his life as a cop.  I have considered suicide because I feel so alone. He hasn't worked in 6 months and we are nearly broke and will be homeless soon.  His SSDI starts next month but it is barely enough to cover our rent and car note.  I am a positive person, but with no support myself I have nothing left to give to him, especially when he treats me so badly.  I have considered leaving him but I could never do that.  He stood by me through my addiction and I feel obligated to stand by him but honestly obligation is all that is keeping me here right now.  I want to give up but I thought that I would reach out on this forum for support hoping that others who have been through this could offer suggestions.  He went back to work two weeks but became sick again and ended up in the hospital with an impacted esophagus.  He is just not getting any better, can't keep food down, and has lost over 50 pounds.  I really need help I am ready to give up.