Need ethical advice on separation involving illness

My partner recently left me after 12 years, we were never married and have a 10 year old daughter together. She told me the reason was that "this relationship isn't working for me anymore". The problem is that she suffers from schizo-affective disorder and major depression and as a result stopped working 10 years ago. Her state was so bad since she stopped working that she was unable to do any house work, very little help with our kid etc. whilst I had to work relentlessly to grow a small business to pay for everything, whilst at the same time doing the house work and raising our kid. The balance was about 95/5.

Now she is demanding 50% of my business which she obviously has no legal right to since we were never married and which I feel is extremely unfair and even disrespectful. However I feel very conflicted on what to do ethically. Her disorder and consequent behavior cost me immeasurable stress, I supported her throughout her illness in every way I knew possible, sacrificing the growth of my company and my dreams in the process, and then she walked out on me.

Yet I know she obviously didn't bring this illness upon herself and in many ways I feel desperately sorry for her and worry about how she will support herself as the mother of my child. And I need to consider the impact of my decision on my daughter. I feel like I need to consult with some sort of ethical counselor on how to proceed with a financial settlement so I can put this behind me, I only want what is right and fair.

Can anyone recommend where I can look for help or have any advice for me?