Wanting to know or understand the right course to take in my situation.

I am on permanent disability and married. I have a home that my husband and I own - our finances are separate - he does NOT claim me as a dependent on his taxes - and is unable to take care of me. I have moved in with my mother - my address is registered with her. She provides 24/7 care for me. I understand that having a contract between she and I would be required to show what I pay her and would be able to show the additional expense of me living in her home is. My spouse provides no support for me. I do pay him a certain amount monthly towards our house payment and pay for my own car insurance etc but he has no financial responsibility for me. Would it be in my best interest to have a legal separation agreement with my spouse in this situation? We are separated for all intense purposes. It is not likely that I will reside in my home with him again. Once I pay my spouse my portion of the mortgage payment and insurance and what I am paying to live with my mother is leaving me with nothing and has put her in a financial strain as well.