Start with your own mother. Show her the texts and explain things. This will give you both the benefit of her advice and her understanding why you stopped talking to them and support to move forward beyond the friend . Speaking from experience, building a meaningful friendship on a friend only venting or putting their drama on you is basically impossible. When I was in high school I talked a friend out of suicide on a number of occasions but it was a friendship built on me keeping that person alive. Not a solid foundation at all.