I"m not sure what to do ...

Hi, I need guidance in what do to with my current position regarding my custody with my children. I married my girlfriend of a little less than 5 years at 24 years old. She had a child from another man that I bacame a part of his life since before he was a year old, he is 12 years old now. Since we've been together she mothered two of my children, a 7 year old boy and a 6 year old daughter. I'm not here to talk about what we've been through together but to get to the point. On 11/4/08 I sustained a back injury on the job that I had been with since I was 18 years old and taken off duty due to the severity of my injury so at that point I was able to focus more on my childrens upbringing which I'm thankful to have had the opportunity to do, seeing the good in the bad of the situation. From that day forward I took on full at home parents duties to the best of my physical ability so I had them every single day until 4/3/11 when after my wife told me we needed a break so I agreed which unfortunately because all my family moved to Arizona I had to go there because I had nowhere else to go. Anyway, because of the animosity and resentment she's expressed to me since my injury which she admitted to me even on text messaging because she had to go back to work to help out because my disability checks were barely 60% of what I was taking home I have had issues with her. The main thing is because I lost my job and was no longer able to send support. It's a little difficult finding a job let alone holding onto one as of late with my injury being my biggest obstacle. Since arriving back into California on 7/19/12, she took my kids away from where we were staying without my knowledge, and in four months I've seen them twice now since ... I had to fight tooth and nail to let them stay the weekend with me two weeks back and I had them this past weekend which I was told will not happen again because she didn't like the fact that I took them to my cousins house for the weekend without telling her. This is such a huge drawn out story and I apologize but my question comes down to this, she went back to her parents ... they're struggling too, to the point where they may lose their house from what she told me is my fault btw and I was staying with my parents in Arizona but I came back here to see my children more and I want to know if it's possible to get a judge to see that I can provide a healthier lifestyle for my kids if they were to come to live with me in Arizona? We have joint custody on everything but my concern is my childrens well being physically, mentally, emotionally. I'm tired of them telling me the things they endure while living where they are, the verbal abuse my daughter recieves because of her weight, the fact that my 12 year old stepson that I see even less than my biological kids shares a room with his brother that used to belong to his nana and her boyfriend and my daughter sharing a bed with her mom because there are 7-8 people in a 3 bedroom house and none of the children have their own room at ages 12,7 & 6. I'll be honest, right now since being back in Cali I am unemployed and have spent my 4 months here at the local library putting in applications, resumes, filing for aid, anything I can to try and get some sort of support to my children but I haven't had any luck so I know if I were to go back to Arizona I have the ability to have help from my parents until I obtain another job to take care of my children. They have expressed interests in their rights as grand parents because they have a home where every child would have their own room plus the means to allow them to live comfortably ... granted that's not something I necessarily want to count on but the offer has been pitched to me and if it benefits my children then I will do what I need to do. I just want to know what my options are.