I am NC with my middle sister (I am the youngest of 3 girls) since Christmas '07. I was pregnant with my third, a surprise-gave birth at 46 (!). She, childless and relationship-less, did not take it well. It was the last straw after years of being treated like a doormat, Death By 10,000 Cuts, etc. I did not call her when my baby was born and two weeks later, told her I needed to take a break from our relationship as I felt my Family Duty Card to her was well and truly punched out. I just came to the point that I could no longer be an endlessly renewable resource for her ego supply. Let her move on to someone else.
I got counseling. It helped a lot. Huge help. I didn't want to be a mean person for cutting her off, "kicking her to the curb". My counselor helped me see that my decision was a response to her behavior and I had nothing to feel guilty about for protecting my own mental health. And ^ she could not make me feel guilty-only I^ could make myself feel guilty. It did take awhile to get my head around that concept, but it is true. Imho, society brainwashes the family duty into everyone, and that is ok as long as everyone is holding to a healthy standard (physically, emotionally, spiritually, financially, etc). But when the dynamics are dysfunctional, why does the rule still apply? It is logical that it shouldn't. All bets are off.
I find it helpful to leave the past in the past. It is easier said than done.
I saw my sister for the first time over this past Christmas at other sister's place. She was visiting our oldest sister and asked to stay over to meet up briefly. (Oldest sister keeps her at an arms length-low contact.) It was her way of asking to see my dd without actually asking to see her (she never asked to see her). So I agreed and we went. I determined to not engage. It was like meeting a superficial acquaintance from way back...we just didn't have a connection anymore. I feel a little better for having seen her; net effect of "so what" rather than guilt that I may have felt a few years ago.
Sorry for the essay!
You need to live your life, as others have said. Don't try to force yourself, (or be forced), into a life's template that doesn't fit you, or that is determined by others. Your choices, boundaries, and the course that you have taken is the right one, no doubts.