Two sisters in their 30's took care of their terminally ill parents. They were always close but after the deaths they are not. Why?

I am the 4 yrs older, we grew up together and always close. I was always the protector of both mom and younger sister, sure us sisters would fight growing up but we loved each other. From the day she was brought home from hospital I LOVED her. She always had a connection with our father and I was closer to our mother. That connection carried through as adults as well. I am more blunt, to the point, bossy, take charge, fix the problem, talk it out, agree to disagree, debate, etc. I will put my own wellbeing on the line to help emotionally, financially, my relationships, etc. to be there for my loved ones. I am 44, single (won't bring anyone in my life since my last parent died, mom due to going through a possible loss of some sort again), I was married for 1 yr during the 2 yrs my mother was dying. I wanted her to see me get married and have a child so she could see and hold my baby and that baby could at least be touched by the love of my life my mother before she passed. Well, due to all the stress during that time I lost both babies and husband left me. So, now I am too old for child. In 10 yr span in my 30's I lost 7 people 6 of those were people who I felt unconditional love from ever....They are gone. Sister got pregnant at 17 & I was 21 (I was so upset more in a protective way) once baby was born I was there and cried out of happiness. She was married, divorced, married had another child and now divorced (she left 2nd husband one yr after mom passed, mom passed after dad by 4 yrs). During mom's two yrs of dying in front of us sister and I lived 10 mins from each other (Sister married with two kids, living the life), we both cared for mom but I took the lead perhaps out of being the older sibling, mom moved in with me, I took a leave from work to care give 24/7 at 36 yrs old, newly married (huge mistake), I worry a lot, younger sister doesn't. I prepare for the "what if's" and have back up plans. She doesn't.. I feel what others are feeling (sad, lonely, upset), she doesn't. It's odd, it's natural for me and I feel or thought it was natural for everyone to feel and notice these same things. I have high expectations of people. I know that is a problem. I never really needed my sister to take care of me or be there for me in our whole lives until mom was passing away. I always naturally took care of my sister my whole life so when I needed her she was not there.... she's never been alone baby at 17, lived with parents, to husband to parents to next husband to me to boyfriend to me, etc. I moved out at 18 yrs old and have been independent since. Caregiving stressed us out to no end and doing so at a young age of 32 yrs old and 36yrs. mom at 60 yrs old. Non stop worry and just ick for 2 yrs. The night mom passed away her and I just left mom (home care facility, not a nursing home), I got a call from sister saying we gotta go NOW, it's happening.. I get in car and she did, we stayed on phone while each driving to mom, I got there first, walking up to the house I kept her on the phone with me and caregiver came outside and put hands on my shoulders and said she's gone.. I covered my ears again with sister on phone, screaming NO NO NO NO, don't say those words, STOP, I dropped to my knees in the street making a sound so hurling that came from the deepest part of my soul. I died at that moment in time. Sister heard all those going on via the phone. within a minute I saw her headlights, hung up the phone and ran to her car, she got out and we stood in street hugging. We had to go into the house to see mom, say goodbye, etc. I was scared to see mom gone, we held hands and I had her go first holding her hand behind her. Kissed moms forehead many time, her cheeks, her hands, everything... I called to have them come pick her up, did the paperwork at the table with coroner, etc. middle of the night it's time to go home and I have an empty house to go to and she goes home to a husband and two kids. Now, if that was me following my sister after our last parent died and knew she was all alone I would of said you come to my place or would you like me to come to your place. I went home alone and mourned for months / years. She had distraction and life around her I had nothing but a home that I took care of my mother in, lost two babies and a husband leave.. that house became a safe place for me and a very dark place. Sister started working out, losing weight, became volunteer fire fighter, had an affair when husband left for overseas work, wasn't around to be a mother of her two boys, started lying, being destructive with herself.. I was working and home in bed depressed... she had no time for me... Decided to leave husband, had to live with me b/c couldn't afford a place on her own, I gave her $6K for divorce, and rental house so her youngest could stay in same school district. Then moved in again with me, losing a job I am right there, needs money again, etc. I feel used and NO LOVE.