Your priority must be to your children: how to protect the future generation from mental illness and a repetition of the older generation's mistakes.
This means that they shouldn't witness the dysfunctional relationships. You have to teach them to do well in school, apply themselves and form stable relationships with others; and be financially secure before having children of their own.
Can you move somewhere else where life is cheaper and you can get away from your parents? If you can afford it, can you seek therapy? Or read books from the library about self-esteem and depression?