Welcome to our forum.
It sounds like you have no small share of challenges; I am especially sorry to hear about the MS. You are facing many things that make poly difficult, such as going through court with your ex. I don't suppose there's any chance your partner and this new woman could spend more time at home with you? Something to talk to them about.
I hope we can be of some help to you on this site. Certainly there is a lot of collective experience and wisdom here. I just wanted to say a few things, and let you know that I'm glad you joined us.
Love means never having to say, "Put down that meat cleaver!"