How do I mind my business w/o cutting my own legs?

A couple of years ago I went to school to continue my studies and had to pay fo my tuition (work study) well long story short I paid for my tuition and met good people along the way....One of the people that I have met and have become close with was my Instructor...we got along very well and even went out a couple of times ( no Love interest) as friends...upon the completion of my studies and in the mist of moving into my own place and starting a new job she was one of the few that extended her services to me and i am forever greatful. Come to find out she ran her own business from home and was extremely overwelmed... between her teaching and her business she was on overdrive...well she asked me if I can ist her in her bussiness and I accepted only on my days off... I have done so for almost 2 yrs.and I most say we work well together and she is a very very smart individual in my eyes..however she is in a realtionship with a chronic alcoholic/ drug addict which affects her in many diiferent ways. Me personally I mind my bussiness and do what I got to do and pay the madness no mind; however its getting to the point where I can't deal with this abuse..although he is not physically abusing her he torments her while we are working and thats where the emotional rollercoaster come to play. She cries, she laugh and than shes a mess and loose concentration....many of her clients are complaining to me even her personal friends and I feel as though the wait of her situation is being imposed on me. I emialed her and expressed my feeling and I even started calling out just not to deal with that mess....but the money is good!! and I have come a long way working with her....My question is do I end this frienship?/ do I quit?/ Do i approach him? or do i mind my business and keep my legs? Keep in mind that she cries me her sorrows than pampers him as though nothing happened and im the one feeling her pain! in a indirect sort of way!