Estranged sister after Mom’s death, am I wrong?

I want to tell my story with hopes of helping myself and others. My Mom moved near me 22 years ago. My Sister and Mom always argued. We enjoyed every weekend together, spoke every night. Two years ago Mom moved into my house. She paid the minimum living expenses, I absorbed $200.00 to keep her savings up for emergencies. My husband and I moved closer to our jobs. In May 2020 my very healthy Mom started to get symptoms. By June she would sleep a lot and was not eating. Her doctor suggested I take her to the emergency room for testing. She first had a UTI and low sodium. They kept her overnight, but the sodium would drop each time they removed the IV. I begged them to find out what was wrong. So she had cancer, much too large to remove, in her abdomen. She was too old to go through chemo. I moved in with her for what could be weeks to months. We did not know. I took good care of her, it was very difficult watching her die, she did not believe she had cancer. A little dementia helped her to forget her struggles, pain and accidents. She fell right in front of me 3 times, it was so traumatic. I had sleepless nights for nearly 10 weeks. Hospice came, but they were little help, especially during Covid. All 22 years, my sister rarely called Mom. She visited 2X well once was to pickup the furniture she wanted from my parents house. She was always happy to meet at Disney, if I shared the cost. If Mom wanted to see her, I had to drive 5 hrs, stay in a hotel, board my dogs. All at my expense. I had a bad fall and so I could no longer drive that far, hence my Sister and Mom did not meet for 7 years. My sister was diagnosed with stage one breast cancer in December 2019. She had aggressive chemo after surgery in March. In July 2020 was the last of 3 chemo treatments. From December to June I sent uplifting cards, gifts and money every week. I also offered to help financially, I would stop putting money in my retirement fund, to help her get the best treatment. My sister said Medicare and insurance covered most everything. Then came caregiving and I shifted my attention to my Mom. I had to text my sister begging her to call Mom, my fear was that she would linger. My sister had told me many times she would not travel to Mom’s funeral, I could plan it. So I did pre plan the funeral, no input was given whatsoever. Oh by the way, my husband purchased Mom’s plot years ago, since she could not afford it. Mom passed away in August. We did a zoom funeral for my sister that was another burden on me finding someone to take off from work to zoom, a video would not do. End of story, I had to pay for the funeral in order to keep the date. The life insurance was more than enough, but we were both beneficiaries. My sister agreed to send me half once she got the money. I printed the forms and sent the death certificate overnight. My sister called and received it. Weeks go by, she had not sent in the paperwork. I asked once a week what could I do to help, my credit card is maxed and I had to postpone my own medical tests, a crown replacement, surgery on my gum. My dogs both got ill, my husband got ill. All from stress. 3 months later, my sister texted me that she will keep the money from the life insurance because it was intended for her and she had cancer, and that was expensive. My first response was oh no, the doctor found more cancer? She said no, they did not, they will monitor. Now, if I add up all of my debts that are not reimbursable it is around 12K. We both got half of Mom’s savings too, so all of my hard work to keep her savings for a nursing home or in home care, went to my sister. I hope this helps someone else to be very careful, do not trust your own family. Take care of yourself first. Get a caregiver’s contract, as suggested. My question, am I wrong to be estranged should I just leave my sister alone, send a Christmas card like normal?