Your plate is too, too full, hon. MS can be devastating - especially if the fatigue symptom begins. If that happens, you won't have the energy to move - let alone deal with an active addict's chaos. Stress alone can cause an MS flare... and you don't want to lose any body function if you can avoid it.
If mom will take you - I vote to go. Jobs, houses and doctors are all replaceable. Your health and happiness are not.
If you are unable to make that choice today - try a women's shelter for resources... counseling, legal, whatever they have available. Talk to other women who have been through this. It can help put things in perspective.
You are in my prayers....
(((Hugs)))