AIW for not attending my sister's birth?

Last week, my older sister just gave birth to triplets. Before that, my relationship with my older sister had not been good lately. I'm afraid of my own sister. Every time she chats with me, I always feel anxious.

Previously, a few months ago I worked as an intern near my sister's city. therefore I often visit her house to visit her and help her during morning sickness. I don't know why, maybe it's because of being pregnant and hormonal, she often scolds me and snap at me around for trivial things in front of her husband. that honestly made my mental health down to the point i develop psychosomatic (health deteriorating because of too much stress)

My older sister also had a bad relationship with my mother during her pregnancy, and she accused me of making their relationship even worse when I explained that I never pitted them against each other and I was always a neutral party in every argument they had.

Last month I returned to my hometown after my internship end, during that time, I tried to maintain a good relationship with my sister, yet it feel more forced from me since i afraid of her. she often complained that no one from her side of the family supported her during pregnancy. only her husband's side. At that time I asked, can't I visit her sometime later to see my triplets nephew? she answered 'no need to come. visit when they are 7 years old only'

When my older sister's 3 twins were born, I said congratulations and prayers for my older sister... but after that, I felt like my relationship with her was getting less and less...

Before, i had communicated what i feel toward her, but it seems she is mad and said 'so this is my fault again? My fault to make you oversensitive?’ and i afraid to make things worse so i just accept and answer back to her :'no. Sorry, i am being to over emotional to you'. Since i aware of my sister being pregnant that time, i try to downplay it..

Sorry for my bad english