A parent committing suicide or dying can be very emotionally and psychologically traumatizing or stunting for children, Killing yourself of-course is a bad thing for them, they will cry themselves to sleep many nights over not having a mother, they might even blame themselves for your passing.
here is a small glimpse into the agony you committing suicide would initially inflict on them.
My point being, that this is the reality of how you decision can affect the people around you, and it's important that you try to understand the gravity of the decision to end your life.
I don't think you are a terrible person for considering suicide in your circumstances, the very fact that you are considering their feelings tells me that you are not a terrible person. You are a victim, and nothing is ever so black and white. I personally consider you catching the bus to be harmful to them, but I don't think it's right that some people should just always suffer and self sacrifice only for the benefit of others. and I don't think it would be life destroying, or prevent them from having a happy life if you were to ctb. unfortunately for us It's human instinct to suffer for others especially your own family, to ensure their survival and the propagation of our genes or something rather. if you do overcome the this nurture instinct and the instinct for self preservation, then it says a lot about how immensely you were suffering and not that you are a bad/immoral person or anything.
you can also can look at it from the perspective of net positives/negatives, if you CTB then will it cause more intense and long lasting suffering in the world than if you were to just live on?